Reference for Bekhorot 50:20

הכא בגיזת בכור בעל מום עסקינן שנתערבו בגיזי חולין ומאן תנא קמא רבי יהודה היא דאמר

but where the expert had not yet permitted it, all unanimously hold [that the wool] is forbidden.<span class="x" onmousemove="('comment',' For it is like an unblemished firstling, and in such a case even Akabya agrees. for if the wool is allowed to be used, he will keep the animal until a blemish appears on it, thus preventing its sacrifice on the altar.');">¹²</span>

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