Mishneh Torah, Negative Mitzvot 1-365

Sugya Map

• Issue: The apparent contradiction between the Torah's prohibition against adding to its commandments (Bal Tosif) and the institution of Mitzvot d'Rabanan (Rabbinic ordinances) by Chazal.
• Nafka Mina(s): Understanding the scope of Rabbinic legislative authority; the halachic nature and binding force of takkanot and gezeirot.
• Primary Sources: Deuteronomy 13:1 ("לא תוסף עליו ולא תגרע ממנו"); Deuteronomy 17:11 ("לא תסור מן הדבר אשר יגידו לך ימין ושמאל"); Mishneh Torah, Negative Mitzvot 1-365 (final paragraphs).

Text Snapshot

"אין הנביא רשאי לחדש דבר ולומר שהקב"ה צוה מצוה זו שתוסף על מצוות התורה... אבל אם בית דין עם הנביא שבאותו הדור הוסיפו מצוה כתקנה או לימוד או גזירה, אין זה תוספת" (Mishneh Torah, Negative Mitzvot 1-365) Dikduk/Leshon Nuance: The Rambam sharply distinguishes between a prophet's inability (אין הנביא רשאי) to claim a new Divine commandment (violating Bal Tosif), and a Beis Din's (with or without a prophet) ability to enact (הוסיפו מצוה) takkanot or gezeirot. The latter are explicitly termed "אין זה תוספת" – not an addition to the Torah's corpus.

Readings

Rambam's Chiddush

The Rambam, both here and in Sefer HaMitzvot (Shoresh Sheni), posits that Bal Tosif forbids only a prophetic claim that a new commandment originates directly from God as part of the 613 mitzvot haTorah. Mitzvot d'Rabanan are distinct: they are human enactments by Beis Din, aimed at safeguarding Torah law or promoting Jewish life, and derive their binding force not from a claim of direct Divine command, but from the Torah's own imperative to obey the Sages (Lo Sasur).

Friction

Kushya

If Bal Tosif prohibits any addition, how can Chazal introduce new obligations like Chanukah candles or Megillah reading? Are these not "additions" to the Divine system?

Terutz

The Rambam resolves this by categorizing. These are not additions to the 613 Divine mitzvot, but rather takkanot – Rabbinic ordinances. Their obligation stems from the d'Oraita command of Lo Sasur (Deuteronomy 17:11) to obey the Sages. Thus, Chazal's enactments are an execution of a Torah mitzvah (obeying them), not an addition to the original 613.

Intertext

• Deuteronomy 17:11: "לא תסור מן הדבר אשר יגידו לך ימין ושמאל" – This verse is the locus classicus for the authority of Chazal, serving as the d'Oraita foundation for adhering to Mitzvot d'Rabanan (Mishneh Torah, Mamrim 1:1).

Psak/Practice

The Rambam's framework establishes that Mitzvot d'Rabanan are fully binding l'halacha, as their observance is a fulfillment of the Torah's command to heed the Sages. This meta-psak heuristic allows for dynamic halachic development and communal stability while rigorously upholding the immutability of the Written Torah.

Takeaway

The Rambam's nuanced distinction between prophetic and judicial authority ensures the Torah's integrity while empowering Chazal to adapt and safeguard Jewish practice through Mitzvot d'Rabanan.