Reference for Bava Metzia 53:12

מאי בינייהו אמר אביי משמעות דורשין איכא בינייהו מר נפקא ליה מאשר תאבד ומר נפקא ליה מומצאתה

on R. Judah's view, and 'sheep' in connection with a lost article, on all views, are [unanswerable] difficulties.<span class="x" onmousemove="('comment',' V. B.K. 54a. The Rabbis maintain that the maker of the pit is not responsible if a man or utensils fall therein, interpreting, 'ox,' but not man, 'ass,' but not utensils. R. Judah, however, maintains that he is responsible for utensils: hence the difficulty, why mention 'ass?' ');">¹²</span>

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