Reference for Yevamot 61:11
קיימי עדים וקאמרי קרוב לה ואת אמרת תתייבם ואין בכך כלום ותו בשתי כיתי עדים נמי ספיקא דרבנן היא דאמרי' אוקי תרי לבהדי תרי ואשה אוקמה אחזקה
-Concerning this statement, surely, it was said: Both Rabbah and R. Joseph maintain that here we are dealing with two groups of witnesses, one of which declare that it<span class="x" onmousemove="('comment',' The letter of divorce. ');"><sup>23</sup></span> was nearer to her and the other declares that it<span class="x" onmousemove="('comment',' The letter of divorce. ');"><sup>23</sup></span> was nearer to him, which creates a doubt involving a Pentateuchal [prohibition] — 29 Our Mishnah, however, speaks of one group.<span class="x" onmousemove="('comment',' One witness of which is contradicting the other. ');"><sup>30</sup></span>