Reference for Niddah 29:19

ותיפוק ליה דהוה נוגע במעת לעת שבנדה

why do the Rabbis declare him clean? And should you reply that this is a case where she did not have the rag in her hand<span class="x" onmousemove="('comment',' So that after she descended from the bed she spent some more time in taking up the rag. ');">¹⁹</span>

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