Menachot 34

Sugya Map

• Issue: Minimum number of doorposts (pitzim) required to obligate a mezuza.
• Nafka Mina(s): Whether a doorway with only one structural doorpost (e.g., a corner entrance or a damaged frame) is chayav in mezuza.
• Primary Sources: Devarim 6:9 ("מזוזות ביתך"), Devarim 11:20 ("מזוזות ביתך"), Shemot 12:22 ("שתי המזוזות"), Menachot 34a.

Text Snapshot

The Gemara presents the dispute between R' Meir and the Rabbanan:

מאי רבי מאיר דתניא: בית שאין לו אלא פצים אחד, רבי מאיר מחייב במזוזה, וחכמים פוטרין. מאי טעמייהו דרבנן? מזוזות כתיב. מאי טעמא דרבי מאיר? דתניא: 'מזוזות' שומע אני מיעוט מזוזות שתים. כשהוא אומר בפרשה שניה 'מזוזות' – שאין תלמוד לומר, הוי ריבוי אחר ריבוי, ואין ריבוי אחר ריבוי אלא למעט. מיעטו הכתוב למזוזה אחת – דברי רבי ישמעאל. רבי עקיבא אומר: אינו צריך, הרי הוא אומר: 'על המשקוף ועל שתי המזוזות' – שאין תלמוד לומר 'שתי'. ומה תלמוד לומר 'שתי'? זה בנה אב: שכל מקום שנאמר 'מזוזות' אינו אלא אחת, עד שיפרט לך הכתוב שתים. (Menachot 34a)

• Dikduk/Leshon: "פצים" (doorpost); "מזוזות" (plural, doorposts); "ריבוי אחר ריבוי" (amplification following an amplification); "מיעטו הכתוב למזוזה אחת" (Scripture restricted it to one doorpost); "זה בנה אב" (this established a paradigm).

Readings

• R' Yishmael: Derives the halakha that one doorpost suffices from ribui achar ribui (Devarim 6:9 & 11:20). The second mention of "מזוזות" is superfluous, and such an amplification restricts the minimum to one.
• R' Akiva: Deems R' Yishmael's drasha "אינו צריך". He establishes a bina av from Shemot 12:22 ("שתי המזוזות"). The word "שתי" is redundant there, thereby teaching that wherever "מזוזות" appears alone, it refers to one, unless "שתי" is specified.
• Rashba (Menachot 34a s.v. ומה תלמוד לומר שתי): Explores why R' Akiva insists on his bina av. He suggests "שתי" in Shemot 12:22 is critical to prevent deriving a one-doorpost rule for the Pesach blood from the mezuza halakha, which R' Akiva's bina av establishes as one.

Friction

• Kushya: If both R' Yishmael and R' Akiva arrive at the same psak (one doorpost suffices), why does R' Akiva reject R' Yishmael's drasha with "אינו צריך"?
• Terutz: The Rashba, among others, implies that R' Akiva’s bina av is a more fundamental and universally applicable principle for interpreting the word "מזוזות" across mitzvot, compared to the ribui achar ribui which might be specific or less foundational.

Intertext

A similar conceptual dispute between ribui achar ribui and bina av appears regarding Sukka walls (Sukkah 2a), where the Gemara questions whether multiple mentions of "סוכה" are l'gufan (for their own sake) or for drasha. The Rashba (ad loc.) contrasts mezuzot with totafot based on this distinction.

Psak/Practice

The Gemara concludes the halakha is like R' Meir (Menachot 34a). However, the Rishonim (e.g., Rif, Rosh on Menachot, Hilchot Mezuza 16:1) generally rule that l'chatchila two doorposts are required. The Shulchan Aruch (Y.D. 289:1) adopts this, but for a doorway with one doorpost (e.g., a keren zavit), one places a mezuza b'lo bracha, indicating a safek or chumra in line with R' Meir's view.

Takeaway

The meticulous drasha of seemingly superfluous words in Torah, even when leading to similar outcomes, reveals distinct interpretive methodologies (ribui achar ribui vs. bina av) that can reflect deeper halachic reasoning.