Mishneh Torah, Negative Mitzvot 1-122

Sugya Map

The Nature of Rabbinic Enactments (Mitzvot DeRabanan)

• Issue: How do Rabbinic injunctions and decrees (תקנות, גזירות) not violate the negative commandment of "לא תוסיף ולא תגרע" (Devarim 13:1) – not to add or subtract from the Torah's mitzvot?
• Nafka Mina(s): Defines the scope and legitimacy of Rabbinic authority; distinguishes between divine revelation and human legislation in Halakha.
• Primary Sources: Devarim 13:1, 17:11; Mishneh Torah, Negative Mitzvot 1-122; Rambam, Sefer HaMitzvot, Shoresh 1 & Lo Ta'aseh 313.

Text Snapshot

The Rambam concludes his enumeration of negative mitzvot with a crucial discussion on Rabbinic law: "All of this will be explained in this text. We are obligated to accept and observe all these commandments which [the Rabbis] instituted, as [implied by Deuteronomy 17:11]: 'Do not deviate from the instructions that they will give you, left or right.' They are not considered to be additions to the commandments of the Torah. [If so,] what was the intention of the Torah's warning (Deuteronomy 13:11): 'Do not add to it and do not detract from it'? That a prophet is not permitted to introduce a new measure and say that the Holy One, blessed be He, commanded this mitzvah to us and that it should be added to the Torah's mitzvot, or [say that He commanded that we] eliminate one of the 613 mitzvot mentioned above. However, if a court, together with the prophet of that age, adds a commandment as an ordinance, a lesson, or as a decree, this is not considered as an addition: He is not saying that the Holy One, blessed be He, commanded us to make an eruv or read the Megillah at its [appointed] time. Were he to say so, he would be adding to the Torah. Instead, we are saying that the prophets and the courts ordained and commanded that the Megillah be read at its [appointed] time in order to recall the praise of the Holy One, blessed be He, the salvation He wrought for us..." Dikduk/Leshon nuance: The core distinction lies in the attribution of the command. A Rabbinic enactment is "ordinance, lesson, or decree" (תקנה, לימוד, גזירה) by human authority, not a false claim of direct Divine command.

Readings

• Rambam, Sefer HaMitzvot, Shoresh Rishon: Defines a "mitzvah" as a direct divine command transmitted by Moshe. This sets the stage for the distinction: Rabbinic laws are not new Sinaitic mitzvot, but expressions of the Torah's meta-command to obey the Sages.
• Rambam, Sefer HaMitzvot, Lo Ta'aseh 313: Explicitly states that the prohibition of Bal Tosif is violated only when one claims a new mitzvah to be of Divine origin. Rabbinic decrees are not subject to Bal Tosif because their authority stems from "לא תסור" (Devarim 17:11), a positive mitzvah to heed the Sages.

Friction

The "Semantic Game" Kushya

• Kushya: If Chazal can ordain new obligations (e.g., Chanukah, Purim), and the Torah warns "לא תוסיף," is this not merely a semantic distinction? Are we not, in effect, adding to the Divine will, regardless of the verbal framing? The Gemara (Rosh Hashanah 19a) grapples with similar questions regarding Hillel's Prozbul.
• Terutz (Rambam): The Rambam's robust response is twofold: First, the authority to enact these decrees is itself a Torah commandment ("לא תסור"^{Devarim 17:11}). Thus, Mitzvot DeRabanan are not additions to the Torah, but implementations of a foundational Torah principle. Second, the intent and declaration are paramount. A prophet claiming a new, divinely ordained mitzvah violates Bal Tosif. A Beis Din instituting a takana or gezeirah for the sake of Torah observance, while explicitly labeling it as Rabbinic, fulfills the Torah's mandate.

Intertext

• Devarim 17:11 ("לא תסור"): This verse is the bedrock of Rabbinic authority. It commands adherence to the Sages' interpretations and decrees, effectively making the observance of Mitzvot DeRabanan a fulfillment of a Torah commandment, not an addition to it.
• Sanhedrin 11a: Elaborates on the binding nature of the Sanhedrin's rulings, even if they appear to contradict plain understanding, reinforcing the principle of "לא תסור."

Psak/Practice

The Rambam's framework here is a fundamental meta-psak heuristic for understanding the entire Halakhic system. It establishes a clear hierarchy: the 613 mitzvot are direct Divine commands; Rabbinic mitzvot are binding because the Torah itself commanded us to obey the Sages. This means Bal Tosif does not restrict the Sages' legislative power but clarifies the nature of their legislation.

Takeaway

Rambam meticulously distinguishes between falsely claiming new Divine commands and legitimately enacting Rabbinic decrees, rooting the latter's authority in the Torah's own command to heed the Sages.