Reference for Yevamot 217:12
והא תניא משום רבי אלעזר אמרו היא וצרתה חולצת היא וצרתה סלקא דעתך אלא לאו או היא או צרתה חולצת לאו תרוצי קמתרצת תריץ הכי היא חולצת צרתה או חולצת או מתייבמת:
shall we then go so far<span class="x" onmousemove="('comment',' Lit., 'rise'. ');"><sup>37</sup></span> as to enact a preventive measure<span class="x" onmousemove="('comment',' Prohibition of the levirate marriage of the rival. ');"><sup>38</sup></span> against a preventive measure?<span class="x" onmousemove="('comment',' Cf. supra note 5. Obviously not. ');"><sup>39</sup></span> But, surely, it was taught: It was stated in the name of R. Eleazar, 'She and her rival perform halizah'; Now can it possibly be imagined that she and her rival [are to perform <i>halizah</i>]? Consequently it must mean,<span class="x" onmousemove="('comment',' Lit., 'but no?' ');"><sup>40</sup></span>