Reference for Bava Kamma 136:3

ודלמא אף על גב דלא אייאש

— I would say, let not this enter your mind. For selling is placed on a par with slaughter: just as in the case of slaughter his act is of practical avail, so also in the case of selling his act should be of practical validity; and if it takes place before Renunciation, what would be the legal validity?<span class="x" onmousemove="('comment',' [Since he conditions the liability of the fourfold and five-fold by the fact that the owner had despaired of the stolen article, it is evident that he agrees with R. Shesheth.] ');">¹</span>

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