Menachot 37

Sugya Map

• Issue: On which arm are Tefillin shel Yad placed?
• Nafka Mina(s): Placement for an iṭer (left-handed person) or sholeiṭ bishnei yadav (ambidextrous person).
• Primary Sources: Devarim 6:8 ("וקשרתם לאות על ידך"), Devarim 6:9 ("וכתבתם על מזוזות ביתך"), Shemot 13:16 ("למען תהיה תורת ה' בפיך כי ביד חזקה הוציאך ה' ממצרים").

Text Snapshot

The Gemara explores derivations for donning tefillin on the left arm:

1. R' Natan: "מה כתיבה בימין אף קשירה בימין, וכיון דקשירה בימין הנחה בשמאל"¹. This gezeira shava links tefillin binding to mezuzah writing, both done by the dominant hand. Since one cannot bind on the same arm it's placed, placement is on the non-dominant (left) arm.
2. Rav Ashi: "מידך כהה"². The verse "על ידך" (Shemot 13:16) is expounded by reading yadkha (ידך) as yad keha (יד כהה), meaning "your weak arm." The dikduk hinges on the final heh implying weakness.

Readings

• Rashi: Explains R' Natan's sevara: "מכלל הנחה בשמאל, דאי הנחה על ימין שוב אינו יכול לקושרה בימין"³. The chiddush is the logical impossibility of simultaneously binding and wearing on the same dominant arm.
• Tosafot: Immediately raises a kushya on R' Natan's sevara concerning a sholeiṭ bishnei yadav. If the sevara is personal, what about one who writes with their right but performs most actions with their left?⁴ The implication is R' Natan's drasha relies on rov (the majority write right-handed), not individual capability.

Friction

• Kushya: Tosafot's query on R' Natan: If kashira (binding) is with the yamin (dominant hand) and rov dictates yemin for writing, what about an individual whose yemin for writing is smol for other actions, or one sholeiṭ bishnei yadav? Does R' Natan's sevara still apply?
• Terutz: The terutz is that R' Natan's derivation "מה כתיבה בימין" establishes the halacha based on the typical mode of action for the mitzvah of writing, setting a general rule for tefillin, not a specific instruction for each person's dominant hand. It's a drasha based on rov, not a personal assessment of strength.

Intertext

The Gemara in Yoma 36b⁵ discusses the semicha of sacrifices, where "ושם ידו על ראש העולה" (Vayikra 1:4) is expounded to require semicha with the right hand, drawing parallels to netila (taking) with the right. This mirrors the Menachot sugya's reliance on rov or textual cues for hand usage.

Psak/Practice

The halacha l'maaseh is that tefillin shel yad are placed on the weaker arm. For an iṭer, this is their right arm. For a sholeiṭ bishnei yadav, the Shulchan Aruch rules he puts them on his left, "כיון דאינו כותב בשתי ידיו בשוה"⁶. This aligns with Rav Ashi's yadkha keha and R' Natan's rov-based interpretation.

Takeaway

The sugya highlights how halacha balances drasha, sevara, and the reality of human physiology (e.g., rov) to determine the practical application of mitzvot.

---

¹ Menachot 37a. ² Menachot 37a. ³ Rashi, Menachot 37a s.v. "מה כתיבה בימין". ⁴ Tosafot, Menachot 37a s.v. "מה כתיבה בימין". ⁵ Yoma 36b. ⁶ Shulchan Aruch, Orach Chaim 27:3.