Midrash for Bekhorot 51:27
דתנן
Said R'Nahman: The law is in accordance with R'Judah<span class="x" onmousemove="('comment',' That Akabya only allows the wool to be used where he slaughtered the firstling and that the difference of opinion does not refer to a dead firstling.');"><sup>14</sup></span>
Sifrei Devarim
(Devarim 15:19) "Every firstling (bechor)": Scripture apprises us that a bechor is to be eaten (by the Cohein) all of its (first) year. This tells me only of an unblemished bechor. Whence do I derive (the same for) a blemished one (that cannot be sacrificed)? From "every bechor." From "You shall not work with the bechor of your bullock, etc." we are taught that it is forbidden to shear or to work with a bechor. This tells me only of an unblemished bechor. Whence do I derive (the same for) a blemished one? From "every bechor."
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