Reference for Niddah 75:29

ר' יהודה אומר דיה וכו'

which childbirth causes to be clean, eighty days<span class="x" onmousemove="('comment',' The child having been born on the day following the (2 + 7 + 2 + 50 = ) 61st day. ');">²⁶</span>

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