Reference for Niddah 108:26

אמר קרא {ויקרא טו } יהיה בהויתו יהא

applies to cycles of a hundred<span class="x" onmousemove="('comment',' The woman is menstrual during the first seven days of the first hundred and is a zabah during the remaining ninety-three days, while the first seven days of the second hundred are counted as the days prescribed after the zibah and in the remaining ninety-three days she is permitted marital intercourse. ');">²³</span>

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