Reference for Niddah 141:37

מכלל דתנא קמא

the question whether the interior of the uterus is unclean.<span class="x" onmousemove="('comment',' According to the first Tanna it is unclean, hence the uncleanness of the blood that was within it when the woman was alive though when it emerged the woman was dead and no longer subject to the uncleanness of menstruation. According to R. Judah it is clean. ');">³³</span>

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