Eruvin 10a

עירובין י׳ ע״א

Learn Eruvin 10a step by step: Aramaic beside English, every question, answer and proof colour-coded.

Open Eruvin 10a in Gemara Clarity

Topic

Eruvin 10a: Does a לחי visible from outside but flush inside count, and how wide may a מבוי entrance be?

Overview

The גמרא tries to defend רבה בר רב הונא's rule that a לחי seen from outside but flush with the wall inside counts. It suggests that the משנה of the small חצר breached into a large one follows רבי, who requires two פסין. A ממה נפשך argument about the 11-אמה measurement knocks this down, and the גמרא concludes that such a לחי does not count. רב יוסף says he never heard רבה בר רב הונא's teaching. אביי reminds him that he himself derived it, among three lessons, from רב הונא's ruling about a לחי extending along an alley wall. The גמרא then rules that such a לחי does count, despite the refutation, because רבי חייא taught a ברייתא saying so. Next, the גמרא returns to the משנה's rule that an entrance wider than ten אמות must be narrowed. It brings רבי יהודה's view that no narrowing is needed, and rejects רב אחי's attempt to set his limit at thirteen and a third אמות from פסי ביראות. Finally, לוי's teaching that one reed in a twenty-אמה entrance is enough is ruled not to be the הלכה. The correct fix, from שמואל in the name of לוי, begins on the next amud.

Opening lines

The steps (23)

1. ResolutionThe case follows רבי, who requires two boards
2. ProofThe ברייתא showing רבי requires two boards
3. RejectionThe explanation works only under certain assumptions
4. ChallengeIf רבי זירא and רבינא are accepted, why eleven?
5. ChallengeEither way, the eleven makes no sense
6. ConclusionThe גמרא concludes that a לחי visible only from outside does not count
7. Statementרב יוסף says he never heard this teaching
8. Proofאביי reminds רב יוסף of רב הונא's ruling about a long לחי
9. Proofרב יוסף's three lessons, including that a לחי visible from outside counts
10. ConclusionThe final ruling: a לחי seen from outside counts
11. ChallengeHow can a refuted view be the הלכה?
12. Resolutionרבי חייא's ברייתא supports the ruling
13. StatementBack to the משנה: a wide entrance must be narrowed
14. Statementאביי cites רבי יהודה: no narrowing needed
15. QuestionHow wide does רבי יהודה allow?
16. Responseרב אחי's first suggestion: thirteen and a third אמות
17. ProofThe קל וחומר from the boards around a well
18. RejectionThe same comparison can prove the opposite
19. RejectionOr the comparison could make the alley even stricter
20. Statementלוי's ברייתא: a reed in the middle of a twenty-אמה alley
21. Conclusionלוי himself rules the הלכה does not follow it
22. ConclusionAnother version: שמואל reports the ruling in לוי's name
23. QuestionIf a reed is not enough, how should one fix the wide alley?