Eruvin 5b

עירובין ה׳ ע״ב

Learn Eruvin 5b step by step: Aramaic beside English, every question, answer and proof colour-coded.

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Topic

A wall piece jutting across a מבוי entrance: when it is a לחי, when it needs another לחי, and how עומד מרובה על הפרוץ and ספק דרבנן make the extra לחי unnecessary

Overview

This amud finishes the ruling of רמי בר חמא about a piece of wall that juts out across the entrance of a מבוי. If it juts out less than four אמות, it counts as a לחי. If it juts out four אמות, it counts as a small מבוי of its own and needs another לחי. רב פפא says the extra לחי goes on the opposite side, and רב הונא בריה דרב יהושע allows it next to the first one if it is a visibly different size. רב הונא בריה דרב יהושע then limits the ruling to an eight-אמה-wide מבוי. In a seven-wide מבוי, the alley is permitted anyway by עומד מרובה על הפרוץ, which he proves with a קל וחומר from a חצר. The גמרא challenges that proof and defends it by explaining that he holds, on his own view, that a מבוי also allows a breach of ten. רב אשי goes further and says even an eight-wide מבוי needs no extra לחי. Either the wall is bigger, or the gap is bigger and the wall is a לחי, or the two are equal, which is a ספק דרבנן and is ruled leniently. The amud ends by opening a new statement of רב about a breached מבוי, which continues on the next amud.

Opening lines

The steps (14)

1. StatementLess than four cubits is a side post, four cubits is an alleyway
2. QuestionWhere does the extra side post go?
3. ResponsePlace it on the opposite side
4. ResponseIt may go alongside if it is visibly different
5. StatementThe rule applies only to an eight-cubit alley; a seven-cubit alley is permitted anyway
6. ProofA courtyard proves that an alley works the same way
7. ChallengeBut a courtyard is more lenient about breaches
8. ResolutionHe holds an alley also allows a breach of ten
9. ChallengeBut this discussion follows רב הונא, who says four
10. ResolutionHe is giving his own opinion
11. Statementרב אשי: even an eight-wide alley needs no extra side post
12. QuestionWhat if the wall and the gap are exactly equal?
13. ResponseAn equal case is a rabbinic doubt, so we are lenient
14. StatementNew case: an alley that was breached