Adding and Subtracting from Torah


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The Scope of the Law

At the beginning of Moshe's legal speech (Devarim 4:2), he warns the nation against adding or subtracting from Hashem's commands:


לֹא תֹסִפוּ עַל הַדָּבָר אֲשֶׁר אָנֹכִי מְצַוֶּה אֶתְכֶם וְלֹא תִגְרְעוּ מִמֶּנּוּ לִשְׁמֹר אֶת מִצְוֺת י״י אֱלֹהֵיכֶם אֲשֶׁר אָנֹכִי מְצַוֶּה אֶתְכֶם.

You shall not add to the word which I command you, neither shall you diminish from it, that you may keep the commandments of Hashem your God which I command you.

The warning is repeated in very similar wording in Devarim 13:1:


אֵת כׇּל הַדָּבָר אֲשֶׁר אָנֹכִי מְצַוֶּה אֶתְכֶם אֹתוֹ תִשְׁמְרוּ לַעֲשׂוֹת לֹא תֹסֵף עָלָיו וְלֹא תִגְרַע מִמֶּנּוּ.

Whatever thing I command you, that you shall observe to do: you shall not add thereto, nor diminish from it.

The verses do not elucidate further, leaving the reader to wonder what exactly is included in the prohibition. How broad is its scope?  Does Moshe refer to changing the form of existing laws or to enacting new ones?  If one performs a commandment more times than required,1 or at a time not mandated,2 would that be a violation? Is voluntary performance of a mitzvah from which one is not obligated included in the prohibition?3 Finally, does the directive include only the total nullification of a law or also individual non-compliance?4

Rabbinic Laws

One of the most troubling questions raised by the prohibition not to add or subtract from Torah relates to Rabbinic law. R. Kahana in Bavli Yevamot 21aYevamot 21aYevamot 90bAbout Bavli Yevamot learns from Vayikra 18:30, "וּשְׁמַרְתֶּם אֶת מִשְׁמַרְתִּי", that one is obligated to make safeguards to Torah law.5  Mishna AvotAvot 1:1About the Mishna similarly teaches the importance of "making fences around Torah". There are also Rabbinic enactments, like the institutions of Chanukkah, Purim, or the washing of hands, which are not even meant to protect Hashem's commands, but are simply totally new laws. Given the prohibition of our verses, though, why are such Rabbinic decrees and safeguards allowed?6 

Biblical Cases

Throughout Tanakh, Biblical figures from Shelomo to Esther appear to change, suspend, or enact new laws.  In building the Mikdash, Shelomo does not suffice with the vessels made for the Mishkan, but adds ten tables and lamps (Melakhim I 7:49). He further celebrates "the holiday" (Sukkot) for fourteen days ( Melakhim I 8:65), rather than the week prescribed in Torah.  Ezra mandates a third of a shekel contribution rather than the half shekel discussed in Torah (Nechemyah 10:33). Eliyahu builds a private altar in an era when these are forbidden (Melakhim I 18:32), and Esther creates an entirely new holiday (Esther 9).  Are any of these actions a transgression of the prohibition of "לֹא תֹסֵף"? None of the leaders are rebuked for their deeds, suggesting that their actions were not problematic.  What, then, might these examples suggest about what is or is not included in the prohibition?

Additional Questions

Our verses raise several other questions as well:

  • Context – The context of the prohibition in Devarim 4 is a discussion of the sin of Baal Peor (and idolatry in general), while the directive in Devarim 13 follows laws regarding sacrificing in "the place which Hashem shall choose" and appears immediately after a warning against child immolation. What might the context teach about the nature of the prohibition?
  • Relationship between Devarim 4 and 13 – Why is the prohibition mentioned twice? Is there any significance to the slight changes in wording?  Why is Devarim 4:2 formulated in the plural while Devarim 13:1 is worded in the singular?
  • Relationship between "לֹא תֹסֵף" and "לֹא תִגְרַע" – Are these two prohibition simply the inverse of one another, or is it possible that the second phrase comes to elaborate on the first, perhaps teaching something about the nature of the prohibited addition?
  • Eternal nature of Torah – What does this prohibition suggest about the eternal nature of Torah? If one assumes that the prohibition is all encompassing, it would seem that it is meant to protect Torah's Divine status, and ensure that it remains exactly as given. However, would a more narrow definition of the prohibition suggest that certain aspects of Torah may indeed change?