Reference for Yevamot 39:20
א"ה חייבי לאוין נמי הא רבי רחמנא יבמתו ומה ראית
by a negative precept.<span class="x" onmousemove="('comment',' A widow to a High Priest. V supra p. 117, n. 6. ');"><sup>48</sup></span> Might it<span class="x" onmousemove="('comment',' The text, His brother's wife. ');"><sup>49</sup></span> not be said [to include also] such as are subject to the penalty of <i>kareth</i>?<span class="x" onmousemove="('comment',' And so subject them also to halizah. ');"><sup>50</sup></span> — Scripture said, If the man like not to take,<span class="x" onmousemove="('comment',' Deut. xxv, 7' ');"><sup>51</sup></span> if he likes, however, he may take her in levirate marriage, [hence it is to be inferred that] whosoever may go up to enter into levirate marriage may also go up to perform <i>halizah</i> and whosoever may not go up to enter into levirate marriage<span class="x" onmousemove="('comment',' Such as those who are subject to kareth. ');"><sup>52</sup></span> may not go up to perform <i>halizah</i> either. If so, the same should apply also to those forbidden by a negative Precept! — But, surely, the All Merciful has included them [by the expression] 'His brother's wife'. What ground is there for such differentiation?<span class="x" onmousemove="('comment',' Lit., 'what did you see', i.e., why include the one and exclude the other? ');"><sup>53</sup></span>