The two variations of this approach differ regarding the total number of plagues and about whether the relatively lighter plagues of כִּנִים, שְׁחִין, and חֹשֶׁךְ are the openings or conclusions of the various groupings.
The first group consists of דָם, צְפַרְדֵּעַ, and כִּנִים, the second includes עָרֹב, דֶּבֶר, and שְׁחִין, and the third is composed of בָּרָד, אַרְבֶּה, and חֹשֶׁךְ.
Sources:R. Yehuda in
Sifre Devarim and
Midrash Tannaim,
9 Lekach Tov,
Rashbam,
R. Avraham b. HaRambam,
Ramban,
R. Bachya,
Ritva,
Ralbag,
Akeidat Yitzchak,
Abarbanel,
Sforno,
Keli Yekar,
R. S"R Hirsch,
Malbim, most commentators
Number of miracles – This approach views the nine plagues from דָם to חֹשֶׁךְ as a distinct unit. Commentators who count ten or eleven miracles,
10 need to still view תַּנִּין as an introductory sign,
11 and the Plague of the Firstborn and Splitting of the Sea as separate from the main cycle of the Plagues.
12 Three Lessons – The Akeidat Yitzchak and Abarbanel
13 explain that each set was designed to teach a different lesson and therefore begins with an explicit statement to that effect.
14 The Plague of
דָם is introduced with "בְּזֹאת תֵּדַע כִּי אֲנִי ה'",
עָרֹב by "לְמַעַן תֵּדַע כִּי אֲנִי ה' בְּקֶרֶב הָאָרֶץ", and
בָּרָד with "בַּעֲבוּר תֵּדַע כִּי אֵין כָּמֹנִי בְּכָל הָאָרֶץ".
15 Thus, the first triad was intended to verify Hashem's existence,
16 the second set to proclaim His providence,
17 and the final group to demonstrate His unique and incomparable abilities.
18 Progression – Ralbag points out that each set was more severe than the previous one.
19 The first triad was composed mainly of nuisances, rather than threatening calamities.
20 The second set more seriously attacked the Egyptian's livestock sources of sustenance and brought bodily pain through the שְׁחִין. The third set, in attacking crops, affected even future livelihood, and the darkness caused more distress. Finally, the last plague brought death itself.
21 Target – Ralbag suggests that in each threesome there was both an attack on the food supply
22and on the Egyptians' own bodies.
23 Agent – The
Tanchuma24 notes that Aharon brings the first set, Moshe initiates the plagues of the final triad, Hashem directly brings עָרֹב, דֶּבֶר, and בְּכוֹרוֹת,
25 while שְׁחִין is brought by both Moshe and Aharon together.
26 Warning – Many of these commentators point out that in each set, the first two plagues were preceded by a warning, while the last one was not.
27 Language and location – Ramban
28 notes that before the first plague of each set, Moshe is told "הִתְיַצֵּב לִפְנֵי פַרְעֹה", while in the second plague the language is "בֹּא אֶל פַּרְעֹה". He explains that the warning for the first wonder of each set took place by the Nile,
29 while the warning for the second plagues of each group was delivered in the palace.
30 Timing – The warning for the first plague of each set took place in the morning.
31 Hardening of Paroh's heart – This division does not account for the shift midway through the Plagues from Paroh himself hardening of his heart to Hashem doing so.
The first group consists of תַנִּין,32 דָם, and צְפַרְדֵּעַ, the second includes כִּנִים, עָרֹב, and דֶּבֶר, the third is composed of שְׁחִין, בָּרָד, and אַרְבֶּה, and the fourth contains חֹשֶׁךְ, בְּכוֹרוֹת, and יַם סוּף.33
Nature of the miracles – R. N"H Wessely suggests that the first wonder of each set served as a warning sign while the other two plagues served as punishments. He thereby explains that there is no warning for כִּנִים, שְׁחִין, and חֹשֶׁךְ, as they themselves constituted warnings for the plagues which followed.
36 Origin – According to R. N"H Wessely, each triad stemmed from a different source: water,
37 land, air, and heavens.
38 Target – R. N"H Wessely notes a progression in the severity of the Plagues from one set to the next. The plagues of the first triad destroyed the fish of the Nile, those of the second group attacked the cattle,
39 the third set ruined the agricultural produce, while the final plagues brought death to humans.
Agent – The pairs of punishment plagues in each set were brought by different agents. Aharon initiated דָם and צְפַרְדֵּעַ, Hashem directly brought עָרֹב and דֶּבֶר, Moshe was responsible for bringing the בָּרָד and אַרְבֶּה, while Hashem and Moshe combine to bring about בְּכוֹרוֹת and יַם סוּף.
40 Hardening of Paroh's heart – According to this approach it is exactly midway through the Plagues (after the first two triads) that Hashem (rather than Paroh himself) begins to harden Paroh's heart.
Magicians – There is a gradual lessening of the magician's roles and status between the triads. In the first cycle the magicians are able to replicate all three wonders. By the second set, though, they can no longer bring the signs. In the third, their stature decreases even further, as due to the שְׁחִין they can no longer even stand before Paroh. In the last set they are missing from the story altogether.
41 Tehillim 78 – Wessely suggests that his structure helps explains why the wonders of the תַּנִּין, כִּנִים, שְׁחִין, and חֹשֶׁךְ are absent from the Psalmist's description of the plagues, as all of these were only preparatory warning signs, not actual plagues.
42