Mishneh Torah, Negative Mitzvot 123-245

Sugya Map

• Issue: Reconciling Mitzvot d'Rabbanan (Rabbinic enactments) with Bal Tosif (Devarim 13:1) – the Torah's prohibition against adding to its commands.
• Nafka Mina: The very legitimacy of Rabbinic authority (divrei sofrim); the theological basis for Halakha's dynamic, yet immutable, nature.
• Primary Sources: Devarim 13:1 ("לא תוסיף עליו ולא תגרע ממנו"); Devarim 17:11 ("לא תסור מן הדבר אשר יגידו לך"); Mishneh Torah, Negative Mitzvot 244-245.

Text Snapshot

Rambam concludes his enumeration of Negative Mitzvot by addressing Rabbinic decrees: "אבל אם בית דין עם נביא שבדור יתקנו מצוה כתקנה, או כהוראה, או כגזירה – אין זה תוספת. שלא אמרו שהקדוש ברוך הוא ציוה אותנו לעשות עירוב או לקרות מגילה בזמנה. שאילו אמרו כן, היו מוסיפים על התורה." (Mishneh Torah, Negative Mitzvot 244-245)

• Dikduk/Leshon Nuance: The precise formulation "שלא אמרו שהקדוש ברוך הוא ציוה אותנו" (they did not say that the Holy One, blessed be He, commanded us) is the critical distinction. It clarifies that Bal Tosif is violated only by attributing new commands directly to Divine revelation, not by enacting human decrees (תקנה, הוראה, גזירה – types of Rabbinic legislation).

Readings

Rambam's Chiddush (Mishneh Torah, Negative Mitzvot 244-245; Sefer HaMitzvot, Shoresh 1)

Rambam asserts Bal Tosif is transgressed when one claims a new mitzvah is min haTorah. Rabbinic enactments, however, are explicitly understood as human decrees, whose observance is mandated by the Torah's command to obey the Sages (לא תסור, Devarim 17:11). The source of the command is Rabbinic; the obligation to obey is Torah-based.

Friction

The "New Obligation" Kushya

If Chazal create a chiyuv (obligation), such as Chanukah candles, which we are obligated to observe min haTorah via Lo Sasur, isn't this effectively an "addition" to the 613 mitzvot, thus violating Bal Tosif?

Rambam's Terutz

Bal Tosif prohibits attributing a new command to God. Chazal never claimed Chanukah was given at Sinai. They instituted it as a takanah; the Torah itself commanded us to obey their enactments (Devarim 17:11). The action is Rabbinic; the meta-obligation to obey is Torah-based.

Intertext

• Sanhedrin 88b: Discusses Bal Tosif regarding adding to the parshiyot of tefillin or species of lulav. This emphasizes Bal Tosif's target: changes to the Torah's defined content, not external Rabbinic safeguards.
• Devarim 17:11: "על פי התורה אשר יורוך... לא תסור מן הדבר אשר יגידו לך ימין ושמאל." This verse is the bedrock of Rabbinic authority.

Psak/Practice

Rambam's framework is foundational for Halakha, permitting dynamic Rabbinic legislation while preserving the Torah's immutability. Divrei sofrim are binding d'Oraita via Lo Sasur, yet not d'Oraita in their origin.

Takeaway

Rambam brilliantly reconciles Bal Tosif with Rabbinic authority: new enactments are human decrees whose observance is Divinely mandated through the command to heed the Sages.