Reference for Bava Batra 126:2

בשלמא לרב זביד היינו דקתני זאת אומרת אלא לרב פפא מאי זאת אומרת קשיא:

R. Papa says: [In order to tell us] that if he desires to build an upper chamber over the apartment, he is at liberty to do so.<span class="x" onmousemove="('comment',' This is explained by the commentators to mean that if the parapet (or the upper storey) falls in, he is at liberty to rebuild it. [R. Gershom's explanation that he may build an upper chamber over the diaita, accords, however, better with our text. cf. n. 4.] ');">³</span> Accepting R. Zebid's view, we understand why Resh Lakish used the expression 'this shows'.<span class="x" onmousemove="('comment',' Because the act of the vendor here in reserving to himself, in virtue of his stipulation, a part of the space over the courtyard is analogous to the act of the Levite in reserving to himself a part of the field. ');">⁴</span>

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