Reference for Chullin 135:37

הוציא את ידו וחתכו ואח"כ שחט את אמו

and also forbidden [to be eaten], but that which is inside is clean,<span class="x" onmousemove="('comment',' The rest of the foetus is rendered permitted by the slaughtering of its dam and likewise free from uncleanness, and it does not suffer any uncleanness by reason of its contact with this limb, because it is a living animal, and a living animal cannot contract uncleanness.');">²¹</span>

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