Reference for Pesachim 46:4

ור"ש דאסר איכא למיפרך מה לחלב שכן הותר מכללו אצל חיה תאמר בגיד שלא הותר מכללו אצל חיה

Alternatively, it is adduced a minori: if heleb, for which there is a penalty of kareth, is permitted for use, how much the more the sinew, for which there is no penalty of kareth. But R'Simeon, who forbids it, [argues]: This can be refuted. As for heleb, that is because It is freed from its general [prohibition] in the case of a beast;<span class="x" onmousemove="('comment',' The heleb of a hayyah (wild or semi-wild animal) is permitted.');">³</span>

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