Sukkah 16b
סוכה ט״ז ב — ד"ה אָמַר רַב חִסְדָּא אָמַר אֲבִימִי
Sukkah 16b:9
Discusses valid methods of constructing sukkah walls and the extent to which unusual or partial partitions qualify. This is directly relevant to evaluating a wall that bows inward without fully collapsing.
אָמַר רַב חִסְדָּא אָמַר אֲבִימִי: מַחְצֶלֶת אַרְבָּעָה וּמַשֶּׁהוּ — מַתֶּרֶת בְּסוּכָּה מִשּׁוּם דּוֹפֶן. הֵיכִי עָבֵיד? תָּלֵי לֵיהּ בָּאֶמְצַע, פָּחוֹת מִשְּׁלֹשָׁה לְמַטָּה וּפָחוֹת מִשְּׁלֹשָׁה לְמַעְלָה, וְכׇל פָּחוֹת מִשְּׁלֹשָׁה כְּלָבוּד דָּמֵי. אָמַר רַבִּי אַמֵּי: פַּס אַרְבָּעָה וּמַשֶּׁהוּ — מַתִּיר בְּסוּכָּה מִשּׁוּם דּוֹפֶן. וּמוֹקֵים לֵיהּ בְּפָחוֹת מִשְּׁלֹשָׁה טְפָחִים סָמוּךְ דּוֹפֶן, וְכׇל פָּחוֹת מִשְּׁלֹשָׁה סָמוּךְ לַדּוֹפֶן כְּלָבוּד דָּמֵי.
§ Rav Ḥisda said that Avimi said: A mat that is four handbreadths and a bit wide can permit the use of a sukka as a wall. The Gemara explains: How does one accomplish this? He suspends it in the middle of a space ten handbreadths high, with less than three handbreadths below it and less than three handbreadths above it. And the principle states: The legal status of any objects that have a gap of less than three handbreadths between them is as if they were joined [lavud]. Therefore, a mat four handbreadths and a bit wide can constitute a fit partition of ten handbreadths. Apropos forming a sukka wall based on the principle of lavud, the Gemara cites that Rabbi Ami said: A board that measures four handbreadths and a bit can permit the use of a sukka, serving as a wall, and it is effective if one establishes it less than three handbreadths from the adjacent wall. And the principle states: The legal status of any objects with a gap of less than three handbreadths between them is as if they were joined.