Why Were Nadav and Avihu Killed/2

Why Were Nadav and Avihu Killed?

Exegetical Approaches

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Overview

Commentators struggle to understand why Nadav and Avihu were deserving of death.  The vast majority of exegetes assume that such a fate must have been a Divine punishment for sin.  Several Midrashic sources assert that the brothers erred in coming too close to the Divine, while others point to problematic ritual procedures and their bringing of an unauthorized offering or flame.  An opinion in Vayikra Rabbah, in contrast, suggests that Nadav and Avihu suffered a vicarious punishment for Aharon's role in the Sin of the Golden Calf.

A minority of commentators propose that Nadav and Avihu were not particularly blameworthy and their death should not be regarded as a punishment.  R"T Granot, elaborating on Rashbam, asserts that, as the brothers performed their normal daily service, they found themselves in the path of Hashem's fire and were killed in a tragic accident.  Philo goes even further to suggest that Nadav and Avihu's actions were actually laudable, as they offered their entire beings to Hashem.  Their death was thus the ultimate sanctification of His name.

Punished for Sin

Nadav and Avihu were killed as a Divine punishment for a sin.

Breached Boundaries

Nadav and Avihu sinned by physically coming too close to the Divine presence.

Sources:Sifra Vayikra10:1About the Sifra Vayikra, opinions in Vayikra Rabbah20:8-10About Vayikra Rabbah, Pesikta DeRav Kahana26:4-9About Pesikta DeRav Kahana, TanchumaBehaalotekha 16About the Tanchuma, Targum Pseudo-JonathanShemot 24:10-11About Targum Pseudo-Jonathan, RashiShemot 24:10Vayikra 10:1-3About R. Shelomo Yitzchaki,¹ AbarbanelVayikra 10:1About R. Yitzchak Abarbanel²

How and when? These sources offer two possibilities as to the nature of the problematic action and when it transpired:

• Entered Holy of Holies – An opinion in the Sifra, Bar Kappara in Vayikra Rabbah, and Abarbanel all fault Nadav and Avihu for entering the Inner Sanctum which was forbidden to all except the high priest on the Day of Atonement.  As this was where Hashem's presence was most strongly felt, unauthorized entry was not only prohibited but also dangerous.
• Saw God – One opinion in Vayikra Rabbah, Tanchuma, Targum Pseudo-Jonathan, and Rashi assert, instead, that Nadav and Avihu were punished not for their actions on the eighth day, but for having "seen God" ("וַיִּרְאוּ אֵת אֱלֹהֵי יִשְׂרָאֵל") at Mount Sinai,³ as described in Shemot 24.⁴  One could similarly explain that the problem was "seeing God" on the eighth day itself; as God's presence had descended and filled the entire Tabernacle, it is possible that the brothers encountered it upon their entry.⁵

Where is "לִפְנֵי י"י"? Those who maintain that the brothers entered the Inner Sanctum point to this phrase as proof, understanding "לִפְנֵי י"י" to refer to the Holy of Holies, where Hashem's presence dwells.⁶  It is also possible that it refers even to the Outer Sanctuary, but due to Hashem's presence there, this too was forbidden.

"בְּקׇרְבָתָם לִפְנֵי י"י" – The emphasis in Vayikra 16's description of the sin on "when they came close to Hashem" might support this approach.  As a result, Aharon is also warned there against entering the Holy of Holies on a regular basis ("וְאַל יָבֹא בְכׇל עֵת אֶל הַקֹּדֶשׁ מִבֵּית לַפָּרֹכֶת").

"אֵשׁ זָרָה" – This phrase is difficult for this position since these sources posit that the problem was not in the offering itself. 

• Those who suggest that the sin occurred on the eighth day might suggest that since the brothers were unauthorized to enter the Inner Sanctum/Tabernacle, any offering they brought there would be considered "foreign".
• Those who say that they were punished for seeing Hashem at Sinai might suggest instead that Nadav and Avihu did sin by bringing a foreign fire, yet this sin was not serious enough to warrant a punishment of death were it not for the fact that it followed their earlier offense.

"אֲשֶׁר לֹא צִוָּה אֹתָם" – This position might read this phrase as referring back to the earlier words "וַיַּקְרִיבוּ לִפְנֵי י"י" rather than the immediately preceding words "אֵשׁ זָרָה" (the verse would thus be a מקרא מסורס).  It was the coming too close to Hashem which had not been commanded.

"הוּא אֲשֶׁר דִּבֶּר י"י לֵאמֹר בִּקְרֹבַי אֶקָּדֵשׁ" – This position could explain this phrase to mean that Hashem had said "Through those who come close, I will be consecrated".  ChizkuniVayikra 10:1-3About R. Chizkiyah b. Manoach asserts that the source of this statement is Hashem's explicit words at Sinai: "וְגַם הַכֹּהֲנִים הַנִּגָּשִׁים אֶל י"י יִתְקַדָּשׁוּ".‎⁷‎

Severity of the punishment – If the brothers actually saw Hashem's presence, their death is easily explained. This is the consequence of getting too close, as Hashem says, "לֹא יִרְאַנִי הָאָדָם וָחָי".‎⁸  Even just entering sacred space is a serious breach and deserves punishment, regardless of a person's motives.

Biblical parallels – Several stories in Tanakh recount similar punishments for breaching boundaries:

• Revelation at Sinai – In Shemot 19, Hashem repeatedly warns the nation not to get too close to the mountain, telling them "כׇּל הַנֹּגֵעַ בָּהָר מוֹת יוּמָת".
• Uzza and the ark – In Shemuel II 6, Uzza touched the Ark to ensure that it did not fall.  Despite his good intentions, this resulted in his death.⁹

The Yom HaKippurim Service – The verses which describe the service of the Day of Atonement connect it to the deaths of Nadav and Avihu.  The Hoil MosheVayikra 10About R. Moshe Yitzchak Ashkenazi asserts that the entire service was necessary to cleanse the Inner Sanctum from the impurity caused by the deaths of Nadav and Avihu.  Alternatively, the directives might be coming to prevent a repeat of the sin, teaching Aharon the proper protocol to safely enter the Inner Sanctum.

Problematic Procedure

Nadav and Avihu violated proper protocol when bringing the incense offering.

Sources:Various opinions in Sifra Vayikra10:1About the Sifra Vayikra, Talmud BavliEiruvin 63aYoma 53aAbout the Bavli, Vayikra Rabbah12:520:8-10About Vayikra Rabbah, Pesikta DeRav Kahana, Targum Pseudo-JonathanVayikra 10:1Vayikra 10:9About Targum Pseudo-Jonathan, R. Saadia GaonVayikra 10:1About R. Saadia Gaon, Lekach TovVayikra 10:1About R. Toviah b. Eliezer, Ibn EzraVayikra 10:1-3About R. Avraham ibn Ezra, R. Yosef Bekhor ShorVayikra 10:1-3Bemidbar 8:19About R. Yosef Bekhor Shor, ChizkuniVayikra 10:1-3About R. Chizkiyah b. Manoach, R. BachyaVayikra 10:1About R. Bachya b. Asher, RalbagVayikra 10:1-3About R. Levi b. Gershom, AbarbanelVayikra 10:1About R. Yitzchak Abarbanel, SefornoVayikra 10:1Vayikra 24:3About R. Ovadyah Seforno, BiurVayikraAbout the Biur (Netivot HaShalom), ShadalVayikra 10:1-3About R. Shemuel David Luzzatto, R. S"R HirschVayikra 10:1-3About R. Samson Raphael Hirsch, R. D"Z Hoffmann, Hoil MosheVayikra 9:22Vayikra 10:3Vayikra 16:1About R. Moshe Yitzchak Ashkenazi

What protocol was transgressed? The brothers either brought an unauthorized offering (אֵשׁ זָרָה" =קְטֹרֶת זָרָה")¹⁰ or it was the flame itself which was the problem.¹¹  The sources disagree regarding what might have been wrong with each:

• Unauthorized offering – Commentators explain this in one of two ways:
• Extra incense – Many of these sources¹² explain that the brothers voluntarily brought their own individual incense offering.¹³ Since Shemot 30:9 states: "לֹא תַעֲלוּ עָלָיו קְטֹרֶת זָרָה", any extra incense offering was considered problematic.¹⁴
• Took Aharon's job – Abarbanel, instead, explains that the brothers were unauthorized to bring the offering, because on the eighth day Aharon alone was supposed to perform all aspects of the service,¹⁵ similar to rituals of the Day of Atonement which are discharged by the high priest alone.¹⁶  Seforno goes further to suggest that throughout the forty years in the Wilderness only the high priest was allowed to bring incense (or perform any other services in the sanctuary) due to Hashem's constant presence in the Tabernacle.
• Improper source of fire –  According to R"Y Bekhor Shor,¹⁷ although a priest is normally allowed to bring fire of his own ("מן ההדיוט"),‎¹⁸‎‎ on this day, Hashem had wanted the sacrifices to be consumed only via His fire¹⁹ so as to glorify His name.²⁰  Alternatively the fire for the incense offering must always be brought from the Altar (as per Vayikra 16:12),²¹ but Nadav and Avihu brought it from a regular source.²²  

"אֲשֶׁר לֹא צִוָּה אֹתָם" – These commentators explain this verse in one of two ways:

• Not commanded – According to the Biur and R. Hirsch, the phrase explains why an "אֵשׁ זָרָה", even if not explicitly prohibited, is problematic. The fact that the fire or incense offering was not commanded is sufficient reason for it to be viewed as wrong. R. Hirsch emphasizes how there is no such thing as subjectivity in sacrificial service; a person cannot act on their own individual desires, but only on the commands of Hashem.²³
• Prohibited – R"Y Bekhor Shor and Chizkuni instead read the verse to mean "which Hashem commanded not [to bring]",²⁴ pointing to the prohibition in Shemot 30:9 against bringing a "foreign incense offering".  The brothers were violating an explicit command and were therefore punished.

Where is "לִפְנֵי י"י"? Most of these sources²⁵ would likely explain that "לִפְנֵי י"י" refers to the Outer Sanctum where the brothers brought the incense on the altar.²⁶

What motivated the brothers? The commentators offer a variety of possible motivations for the brothers, some positive, some less so:

• Love of God – According to the Biur, R. Hirsch and R. D"Z Hoffmann, Nadav and Avihu brought an extra sacrifice out of a desire for closeness to Hashem.²⁷ 
• Concern for Hashem's honor – An opinion in the Sifra²⁸ states that when the brothers saw that Aharon had finished his service but Hashem's presence had not descended, they worried and decided to bring fire of their own to help it along.²⁹  Though their intentions were positive, their actions suggested a lack of faith and led to a lessening of God's glory.³⁰
• Mistaken assumptions – Seforno suggests that Nadav and Avihu assumed that just like incense is burned after the Daily Offering to honor the arrival of Hashem's presence, so too an incense offering was called for at the Mishkan's inauguration after Hashem's fire descended and His glory was revealed.³¹  According to R"Y Bekhor Shor, too, the brothers actions were based on a misunderstanding.  They simply did not realize that Hashem did not want them to bring of their own fire on this day.³²
• Arrogance – Shadal, in contrast, attributes the brothers' actions to excessive haughtiness and a desire to be honored like their father.³³ Since they had not been assigned to perform any particular service, they took upon themselves one of the most prestigious rituals.

"בִּקְרֹבַי אֶקָּדֵשׁ" – To whom does this refer?

• Nadav and Avihu – R"Y Bekhor Shor, the Biur, R. Hirsch, and R. D"Z Hoffman all read the term "קְרֹבַי" as referring to Nadav and Avihu, who, despite their error, were still considered close to Hashem.³⁴  Hashem was sanctified through them, since the nation realized that if such holy individuals could be punished, they certainly needed to be fastidious in their own observance so as to avoid similar punishment.
• Aharon – Those who read the brothers less positively might explain, as does RashbamVayikra 10:1-3About R. Shemuel b. Meir, that the term refers not to Nadav and Avihu, but to Aharon, who was being commanded to sanctify Hashem's name by continuing with Hashem's service rather than mourning over the death of his sons.³⁵

Severity of punishment

• Serious sin –Those who view the sin as relating to an unauthorized incense might suggest that this was a serious sin, especially since a "קְטֹרֶת זָרָה" is explicitly prohibited. In the story of Korach, too, unauthorized incense offerings result in death. 
• High expectations – The Biur, R. Hirsch, and the Hoil Moshe, nonetheless, assert that the brothers were punished so severely only due to their stature; Hashem is always more exacting with His loved ones.³⁶
• Lesson to others –  Those who assert that the sin was simply doing a "not commanded" action have a harder time explaining the punishment.  R"Y Bekhor Shor and Ralbag maintains that it needed to be severe to teach the nation the importance of being exacting in observing the laws of sacrifices.³⁷ Seeing how Hashem punished even those who were close to him, taught laymen how much more they needed to fear God.

Context – prohibition to drink wine – According to this approach, the prohibition of officiating priests drinking wine follows our story as another warning of the need to be exacting and careful (and thus unimpaired by drink) when serving in the Mikdash.

Vicarious Punishment

Aharon's sons died, not for their own crime, but as a punishment to Aharon for his participation in the Sin of the Golden Calf.

Sources:perhaps Vayikra Rabbah7:1About Vayikra Rabbah and RashiDevarim 9:20About R. Shelomo Yitzchaki³⁸

Sins of the father – This approach maintains that sometimes Hashem punishes children for their parent's sins. Thus, even though it was Aharon who sinned, it was his children who were killed. For a full discussion of the issue and various explanations of the phenomenon, see Are Children Punished for Parents' Sins?

Why now? Or HaChayyim asserts that before Aharon could serve as high priest in the Mishkan, his previous sins needed to be atoned for and punished.  He claims that, for this reason, the Torah links the description of the Service on the Day of Atonement to Nadav and Avihu's death; only after their death and his own atonement could Aharon serve and atone for others.³⁹

"הוּא אֲשֶׁר דִּבֶּר י"י לֵאמֹר בִּקְרֹבַי אֶקָּדֵשׁ" – Rashi claims that Hashem made this statement when He first relayed the commands regarding the consecration of the Tabernacle in Shemot 29,⁴⁰ saying: "וְנֹעַדְתִּי שָׁמָּה לִבְנֵי יִשְׂרָאֵל וְנִקְדַּשׁ בִּכְבֹדִי".‎⁴¹  Although, at that point, the brothers had not yet done anything at all blameworthy, their deaths could already be decreed, since they were a punishment for the earlier act of Aharon.⁴²  However, since they themselves were innocent, the brothers are called "קְרֹבַי".

Severity of the punishment – Since Aharon's actions led others to worship the Calf, a harsh punishment would seem warranted.  For a discussion of Aharon's actions and the nature of the nation's sin, see Sin of the Golden Calf

"וַיַּקְרִיבוּ לִפְנֵי י"י אֵשׁ זָרָה אֲשֶׁר לֹא צִוָּה אֹתָם" – This approach must explain why the verses imply that Nadav and Avihu erred, even though they themselves did nothing wrong.  It might explain that the brothers did mistakenly bring a foreign fire, but since this was not prohibited (and merely not commanded) it would not have been considered a capital crime were it not that Hashem wanted to punish their father.

Where is "לִפְנֵי י"י"? This position would likely understand this term to refer to the Outer Sanctum, where the brothers were permitted to enter.

"וַיִּדֹּם אַהֲרֹן" – This approach might explain that Aharon was silent, recognizing that the decree was his fault.

Work Accident

Nadav and Avihu's actions alone would not have warranted their death, but their being in the wrong place at the wrong time caused them to be consumed by Hashem's fire.

Sources:RashbamVayikra 9:23-24Vayikra 10:1-3About R. Shemuel b. Meir,⁴³ R"T Granot⁴⁴

Verses out of order – Rashbam posits that the story of Nadav and Avihu really occurred before Hashem's fire consumed Aharon's offerings as described in Vayikra 9:24, but is told only later for literary reasons.⁴⁵  It is on this backdrop that he explains the rest of the story.

The standard incense offering – According to Rashbam, Nadav and Avihu were not bringing an unauthorized incense, but only the regular offering brought every morning.  As such, Nadav and Avihu would likely have had no way of knowing that their actions were not desired.

"אֵשׁ זָרָה" – The brothers' only mistake was in bringing "foreign fire" rather than waiting for Heavenly fire to consume the incense.  Rashbam explains that although a priest is normally allowed to bring fire of his own ("אש מן ההדיוט"),‎ during the Mishkan's consecration, Hashem had wanted to glorify His name by having all of the sacrifices be consumed via Divine fire.  R. Granot suggests, instead, that the brothers were impatient for Hashem's revelation and tried to "hurry the end".

"אֲשֶׁר לֹא צִוָּה אֹתָם" – Rashbam adds the word "היום", explaining that it was only on this day that the brothers' actions were not commanded; on any other day they would have been permitted.

"וַתֵּצֵא אֵשׁ מִלִּפְנֵי י"י" – Rashbam identifies this fire with the fire described a couple of verses earlier in Vayikra 9:24.⁴⁶ According to him, the fire that consumed Aharon's offerings on the outer altar was the very same fire which killed the brothers.⁴⁷  This fire emanated from "before God", or the Inner Sanctum, where Hashem's presence dwells.  As such, the Heavenly fire did not come down vertically from the heavens, but rather traveled horizontally from the Holy of Holies to the Outer Sanctum (where it met the brothers), as it made its way to the Copper Altar.

Severity of the punishment – According to this approach, the fire that killed Nadav and Avihu was not intended to punish them, but only simply to consume Aharon's sacrifices.  Unfortunately, they happened to be in the way and suffered the natural consequences.  In other words, it was a tragic accident rather than a punishment.

Why not bring the fire later? This approach must contend with the question of why Hashem allowed such an accident, rather than waiting to bring the fire when no one was in the way.  It could respond that since the brothers had sinned, albeit erroneously, they were not worthy of a miracle to save them. Alternatively, since the entire nation was outside waiting for Hashem's glory to appear, there would have been a great desecration of His name if there had been a delay.

"בִּקְרֹבַי אֶקָּדֵשׁ" – To whom does this refer? According to this approach, it is understandable that the brothers are referred to as "close to Hashem" since they died without major sin.⁴⁸

Biblical parallels – Other catastrophes in Tanakh have also been viewed by some as natural consequences rather than punishments. For example, see Mystery at the Malon for Abarbanel's reading of Moshe's near death being the result of lack of preparation for prophecy.  Netziv similarly explains the death of the "Ma'apilim" in Bemidbar 14 not as a punishment, but as the natural result of war.

Sanctified to God

Nadav and Avihu's deaths were not a punishment but rather a sanctifying of their souls to Hashem.

Sources:PhiloOn Dreams 2:67On Flight and Finding, 59About Philo, perhaps HaKetav VeHaKabbalah

"בִּקְרֹבַי אֶקָּדֵשׁ" – To whom does this refer? This approach rests on the understanding that this phrase refers to Nadav and Avihu who are described as "close to Hashem".  If they are referred to as such in death, it is impossible that their actions were seen as sinful in the eyes of Hashem.  Moreover, if their deaths served to sanctify Hashem, it must not have been a punishment but some form of elevation.

"וַיַּקְרִיבוּ... אֵשׁ זָרָה אֲשֶׁר לֹא צִוָּה אֹתָם"

• Philo reads this fire metaphorically to refer to the passion of Nadav and Avihu's love for God which they offered up to Him with their whole being.  It is referred to as a "foreign" fire because it was "foreign to earthly existence since it belonged to the realm of God".
• More simply, the verse could mean that Nadav and Avihu offered a non-obligatory, or voluntary, sacrifice.  It was called foreign because it had not been commanded.  According to this reading, the phrase "אֲשֶׁר לֹא צִוָּה אֹתָם" comes to explain the term "אֵשׁ זָרָה". It does not have a negative connotation, but rather comes to highlight the brothers' desire to give even more to Hashem than He had required.

"לִפְנֵי י"י" – This position might explain the threefold repetition of the phrase "לִפְנֵי י"י" as coming to emphasize the brothers' desire to come close to Hashem and be before Him.

What motivated the brothers? HaKetav VeHaKabbalah quotes the Sifra that "כיון שראו אש חדשה... עמדו להוסיף אהבה על אהבה".  Upon seeing Hashem's presence and fire descend, they felt a need to reciprocate and offer something up to Him in return.

Death is not always punishment – Philo compares the brothers' death to a "whole burnt offering" which rises heavenwards.  According to him, in Nadav and Avihu's religious fervor, death would not have been viewed as a punishment, but as a sanctification of their being to God.

Biblical parallels – This approach might compare Nadav and Avihu to Chanokh, whom Hashem "took" because he "walked with God".  [See Bereshit 5:24: "וַיִּתְהַלֵּךְ חֲנוֹךְ אֶת הָאֱלֹהִים וְאֵינֶנּוּ כִּי לָקַח אֹתוֹ אֱלֹהִים"].  Accordingly, in neither case should death be viewed negatively.  Rather, due to their piety, sometimes the righteous are prematurely taken to be with Hashem.

"וַתֹּאכַל אוֹתָם" – HaKetav VeHaKabbalah points out that since the verse states that Nadav and Avihu died, the phrase "and it consumed them" must come to teach something beyond the fact of their death.⁴⁹ He suggests that the choice of verb connotes an acceptance of something with joy, and refers to the fact that Hashem accepted the brothers' souls with favor.

¹ In his comments on Vayikra 10, Rashi also brings the opinions of R. Eliezer and R. Yishmael that Nadav and Avihu sinned in teaching halakhah before their teacher or in entering the Mikdash while drunk.

² Abarbanel points to several sins, one of which was entering the Holy of Holies.

³ Both Rashi and Targum Pseudo-Jonathan attribute more than one sin to Nadav and Avihu.  They likely maintain that the brothers were punished for multiple actions.

⁴ Rashi explains that Hashem waited to kill them because He did not want to turn the happiness of the day of receiving the Torah into a tragedy.  It is not clear, however, why He would instead choose to kill them on the day of the Consecration of the Mishkan, a similarly festive occasion.

⁵ Shemot 40:35 records that when Hashem's glory filled the Tabernacle, even Moshe himself could not enter.

⁶ See Shemot 16:33-34 where the term "לִפְנֵי י"י" appears to be equated with "לִפְנֵי הָעֵדֻת", referring to the ark, and thus must refer to the Inner Sanctum.

⁷ In context, the warning applies only to revelation and mandates proper preparations for those who were to approach Hashem, lest they be punished.

⁸ See Shemot 33:20.

⁹ This story was likely chosen as the haftarah for Parashat Shemini due to the similarities between the stories. In both cases, there is a celebration for a consecration of the Tabernacle/Ark in which an undefined sin relating to improper worship is punished by death. It is interesting to note that the name of Uzza's father is Avinadav, a combination of the names Nadav and Avihu.

¹⁰ The Biur explains that the term "אֵשׁ" is really just a variation of the term "אִשֶּׁה לַי"י", another name for sacrifices. Cf. Chizkuni who claims that it is referred to as fire since all such offerings must be accompanied by fire. R. D"Z Hoffmann adds that it was not called a "קטורת זרה" since it was not brought on the incense altar.

¹¹ Vayikra Rabbah lists other possible wrongdoings as well, such as: not wearing the proper priestly vestments, failing to wash before service, or entering the Mishkan while intoxicated.  There is no explicit mention of any of these, though the fact that the prohibition to drink wine immediately follows the story might be brought as support that the crime involved drinking.  The Midrash is probably motivated by the fact that each of these transgressions is punishable by death, making  it clear why the brothers were killed. See Shemot 28:43, Shemot 30:21 and Vayikra 10:9.

¹² See Chizkuni, the Biur, Shadal, R. S"R Hirsch, R. D"Z Hoffmann, and the Hoil Moshe.

¹³ In other words, the offering described in the verses was not the regular morning incense offering, but a separate personal offering.  Cf. Rashbam who disagrees and claims that it was the regular daily offering.

¹⁴ It should be noted, however, that not all agree that this verse refers to an unauthorized offering.  See Onkelos and Ibn Ezra who assert that it refers to an offering which consisted of the wrong spices.

¹⁵ He also raises the possibility that Moshe alone was supposed to serve as high priest that day and bring the incense. Either way, it was not Nadav and Avihu's task.

¹⁶ See also R"M Spiegelman, "פרשת שמיני - חטאם של בני אהרן", who suggests that Nadav and Avihu mistakenly viewed themselves as high priests, since also they were anointed. Thus, they thought that they too were allowed to participate in the service of the eighth day.

¹⁷ Cf. Rashbam below.

¹⁸ See the BavliYoma 21bAbout the Bavli which derives from Vayikra 1:7: "וְנָתְנוּ בְּנֵי אַהֲרֹן הַכֹּהֵן אֵשׁ עַל הַמִּזְבֵּחַ", that the priests themselves are normally commanded to bring the fire, even though there is already fire on the altar from Hashem.

¹⁹ R. Yosef Bekhor Shor asserts that the story of Nadav and Avihu is not recorded in its chronological place and that they really brought their incense before the fire mentioned in Vayikra 9:24 came down to consume Aharon's offerings.  As such, it was very possible that the nation would conclude that it was their fire, and not Hashem's, that consumed the other offerings, thereby lessening God's glory. [Even if one disagrees, and maintains that the the verses are in chronological order, one might still say that, on this first day, Hashem wanted all offerings to be consumed by His miraculous fire.]

²⁰ The Lekach Tov disagrees with Rashbam, asserting that even on this day it would have been permitted to bring fire from a "הדיוט", but the brothers should not have deduced this by themselves and should have instead asked Moshe. It was the fact that they did not first obtain permission which was really problematic. This is presumably what R. Eliezer in the Bavli means as well when he faults Nadav and Avihu "שהורו הלכה בפני משה רבן" (for teaching the law before their master, Moshe).

²¹ See the Raavad (as quoted by the RitvaYoma 53aAbout R. Yom Tov b. Ashbel) who suggests that the brothers erroneously assumed that what was true regarding the Outer Altar (where a priest is supposed to bring of his own fire) was also true of the Altar of Incense.

²² Ralbag also raises the possibility that the brothers might have even taken fire from the Outside Altar, but from the wrong place on it.

²³ See the Netziv similarly, "ואמרה תורה דאע"ג דאהבת ה' יקרה היא בעיני ה' אבל לא בזה הדרך אשר לא צוה". It is probable that both R. Hirsch and the Netziv are engaged in polemic with the Reform movement, and are hinting that worship of God is not about getting close to Hashem in whatever way speaks to each individual, but rather about following God's commands.

²⁴ As support for rearranging the words of the verse in such a manner, R"Y Bekhor Shor points to Yirmeyahu 7:31, where the similar phrase "אֲשֶׁר לֹא צִוִּיתִי", also means "אשר צויתי לא" (that I prohibited) and not simply "that I did not command."

²⁵ Abarbanel, the Biur, R. D"Z Hoffmann, and the Hoil Moshe do think that they brought it on the inner altar, with Abarbanel pointing to this as a second sin. The Biur, however, points out that the prohibition against entering was not commanded until after the brothers' death in Vayikra 16:12.  As such, they were not culpable for unauthorized entry, but only for unauthorized offerings.

²⁶ Ibn Ezra uniquely understands the phrase "וַיָּמֻתוּ לִפְנֵי י"י" to refer not to a geographical location, but a spiritual one. The brothers acted and died "before God", thinking that they were doing something pleasing to Him.

²⁷ R. Hirsch nonetheless criticizes the brothers for forgetting their role as priests, whose job is to serve the nation and be their representatives before Hashem.  In such a role there is no room for individual self-expression.

²⁸ R. Bachya explains similarly, that they feared that Hashem's fire on the Altar was not sufficient to consume everything and decided to contribute their own fire.

²⁹ This can be compared to Moshe's sin in hitting the rock. Moshe, fearing that no water was to come from speech alone, decided to hit the rock to bring forth water.  See Moshe's Misstep and Mei Merivah.  See also R"T Granot below.

³⁰ Also those who view the brothers as intoxicated might assume that nonetheless their motives were positive, thinking that it was best to serve Hashem when uninhibited, or that drinking would raise them to higher levels of religious fervor.  This, however, is not how Hashem wants to be worshiped.

³¹ R"Y Grossman, in his article, "פרשת שמיני - היום השמיני וחטא נדב ואביהו" takes a similar tack, suggesting that Nadav and Avihu worried that the nation was unworthy of having direct contact with Hashem.  Thus, as soon as He revealed Himself through the fire, they quickly brought an incense offering to mask the revelation. [So, too, on the Day of Atonement, the high priest must bring a cloud of incense, "כִּי בֶּעָנָן אֵרָאֶה עַל הַכַּפֹּרֶת."]

³² Since on other days this would have been allowed, and Hashem had never told them otherwise, it would have been easy to err.  This, however, makes it difficult to understand the punishment.  The Bavli and Lekach Tov therefore explain that the brothers were really punished for making their own assumptions and not verifying them with Moshe.

³³ See also the opinion in the Sifra which states, "מה תלמוד לומר בני אהרן? שלא חלקו כבוד לאהרן" and Bavli Sanhedrin which presents Nadav and Avihu as waiting for their father and Moshe to die so they could lead the nation.
Cf. the Hoil Moshe who suggests that the brothers were actually trying to give their father honor. Seeing that Hashem's glory descended only after Moshe came to the Tabernacle to pray, they thought that others would think that their father was unworthy of bringing God's presence.  As such, they thought to bring an incense offering to prove that their immediate family, too, was desired by God.

³⁴ Shadal, who views the brothers more negatively, might explain instead that Hashem referred to the brothers as "קְרֹבַי" only because their position as priests had elevated them closer to Hashem. This, though, made their fall from grace all the greater. In punishing them Hashem sanctified himself, demonstrating to all that nobody is immune to punishment.

³⁵ Rashbam points to Vayikra 21:10-12 and the laws of priestly mourning as the source for when this was said. The verse there states, "וּמִן הַמִּקְדָּשׁ לֹא יֵצֵא וְלֹא יְחַלֵּל אֵת מִקְדַּשׁ", teaching that if the priest does continue his service despite the death of a loved one, he will sanctify Hashem.  These verses, however, appear only eleven chapters later.  Thus, Rashbam is forced to appeal to the principle of "אין מוקדם ומאוחר בתורה".  This is, in fact, the only instance in his commentary in which he explicitly cites this principle.

³⁶ The Biur compares their punishment to that of Moshe and Aharon at Mei Merivah, whose sin merited disproportionately severe consequences. He notes that there too the verse states "וַיִּקָּדֵשׁ בָּם".‎  For elaboration, see Moshe's Misstep and Mei Merivah.

³⁷ See, similarly, R. Hirsch regarding the necessity of teaching the nation of the dangers of subjective worship.  If even people of the stature of Nadav and Avihu are punished for such actions, all the more so regular people.

³⁸ Neither of these sources state explicitly that Nadav and Avihu were killed solely for Aharon's sin, but both explain that their death was a punishment to Aharon for making the Calf.  See also the Hoil Moshe who asserts that Aharon's sin indirectly caused that of his sons, and that Aharon himself believed that he had caused their deaths.

³⁹ For a discussion of the view that the Tabernacle and the general service of the eighth day (Vayikra 9) served to atone for the Sin of the Golden Calf, see Purpose of the Mishkan.  The position developed here is more radical version of that approach.

⁴⁰ Rashi consistently looks for a textual basis anywhere the text alludes back to speech that was not recorded previously. For other examples, see his comments on Bereshit 32:13, Shemot 14:12, Bemidbar 11:12, Devarim 6:19, and many others. For further discussion, see Invoking Hashem's Name Without Explicit Divine Sanction.

⁴¹ Rashi is following Bavli Zevachim 115b, which says the verse should be read as if written "במכובדיי".

⁴² According to Rashi, the Mishkan was commanded only after the Sin of the Golden Calf.  For elaboration, see Purpose of the Mishkan.

⁴³ Rashbam is not explicit, but this is the general direction of his comments.

⁴⁴ See his article, "פרשת שמיני - גילוי כבוד ה' על המזבח ומות נדב ואביהוא" where he expands on Rashbam's commentary to the story.

⁴⁵ He reads Vayikra 9:24 as a general statement introducing the story which is then elaborated upon.  He compares our verses to the similar phenomenon of "כולל ואחר כך מפרש" in Shemot 19:8-10 and Shofetim 17:1-4.

⁴⁶ See above note that Rashbam reads Vayikra 9:24 and the description of the fire there as a general introduction to the rest of the story.  Afterwards the verses backtrack to recount the event in order.

⁴⁷ See also Josephus, Antiquities 3:8:6-7, who also identifies the fires as one and the same.

⁴⁸ Rashbam himself does not actually think the verse refers to the brothers but to Aharon who sanctified Hashem's name when he continued with Hashem's service rather than mourning.

⁴⁹ He points out that in the story of Korach's rebellion, when the 250 people are consumed by fire the verse uses only one verb, "consumed", leaving out "and they died".  The doubling in our story, therefore, might be significant.