Reference for Yevamot 155:16

אי אמרת בשלמא עובר לאו ירך אמו הוא הוה ליה כמפריש שתי חטאות לאחריות ואמר רב אושעיא הפריש שתי חטאות לאחריות מתכפר באחת מהן והשניה תרעה

of its mother, the former is like the young of a sin-offering,<span class="x" onmousemove="('comment',' Which was without child at the time of its dedication. ');">⁵²</span> and the young of a sin-offering is sent to die!<span class="x" onmousemove="('comment',' How', then, could R. Johanan state that atonement may be made with either? ');">⁵³</span> The other remained silent. 'Is it not possible', the first said to him, 'that there<span class="x" onmousemove="('comment',' The ruling about the ascription of the Egyptian child to its mother, reported in the name of R. Johanan. ');">⁵⁴</span> it is different.<span class="x" onmousemove="('comment',' From other cases. While elsewhere the child may be ascribed to its father, in the case spoken of by R. Johanan it is ascribed to the mother. ');">⁵⁵</span>

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