Reference for Shevuot 35:6

א"ל רב אדא בר מתנא לרבא לעולם אימא לך בשלא סמוך לווסתה ואפרישה וכי תימא פרישה למה לי הא תנא ליה הא איצטריך לאשמועינן נמצא על שלה טמאים בספק ופטורין מן הקרבן ואיידי דבעי מיתנא נמצא על שלה תנא נמי נמצא על שלו

R'Adda B'Mattenah said to Raba: [No!] Really I can say to you, it refers to the time not near her period, and to withdrawing.<span class="x" onmousemove="('comment',' He brings the sacrifice for withdrawing immediately, when she tells him she is unclean; for entering he is not liable, because it was not near her period.');">¹¹</span> And should you ask, what need is there to state the law of withdrawing, since it has already been stated?<span class="x" onmousemove="('comment',' In our Mishnah, supra 14b.');">¹²</span> [I may reply,] because it is necessary to tell us: [blood is] found on her [rag after cohabitation],<span class="x" onmousemove="('comment',' Not immediately, but after a short interval; Nid. 14a.');">¹³</span>

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