Reference for Eruvin 178:9

והא דיורין אמרת לן אי אמרי לכו דיורין הכי אמרי לכו ל"ש אלא שיש מחיצה ראויה לדירה על זה ומחיצה ראויה לדירה על זה דגדול מישתרי בגיפופי וקטן נפרץ במלואו

And it was in connection with this that you told us: Rab Judah in the name of Samuel stated: They learned this<span class="x" onmousemove="('comment',' That the movement of objects is forbidden on the smaller roof.');">²¹</span> only in the case where there were dwellers on the one as well as on the other<span class="x" onmousemove="('comment',' And these freely walked across from their own roof to that of their neighbours.');">²²</span> so that the imaginary partition of the smaller roof<span class="x" onmousemove="('comment',' The presumed upward extension of the wall supporting it.');">²³</span>

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