Reference for Yevamot 107:19

אמר ליה רב אחא מדפתי לרבינא אטו נדה ואשת אח בחיי אוסרן הוא דאין להם היתר אבל לאחר מכאן יש להם היתר נדה

— Deduction is rather made<span class="x" onmousemove="('comment',' V. supra p. 359, n. 3. ');">⁵⁵</span> from the menstruant<span class="x" onmousemove="('comment',' Who may be a stranger. ');">⁵⁶</span> and a father's sister and a mother's sister. Those however [it may be objected] are in a different category since the prohibition is natural!<span class="x" onmousemove="('comment',' It is not due to any human act. ');">⁵⁷</span> — The deduction<span class="x" onmousemove="('comment',' V. supra p. 359, n. 3. ');">⁵⁵</span> is rather made from the menstruant and a brother's wife; since no<span class="x" onmousemove="('comment',' Lit., 'for what'. ');">⁵⁸</span> objection can be raised [against the two].<span class="x" onmousemove="('comment',' A brother's wife is a relative forbidden through marriage and consequently the second objection (v. supra p. 359. n. 1) cannot be advanced; while the first objection (v. supra p. 359, n. 8) and the third objection (v. supra n. 7) cannot be raised in view of the law of the menstruant. ');">⁵⁹</span> R. Aha son of R. Ika demurred: A menstruant and a brother's wife are different,<span class="x" onmousemove="('comment',' From the other women one is forbidden to marry. ');">⁶⁰</span> since marriage with them cannot be permitted during the lifetime of the man who caused their prohibition! Would you, then, apply [their restrictions] to a married woman who might be permitted to marry even during the lifetime of the man who caused her prohibition?<span class="x" onmousemove="('comment',' I.e., her husband, if he divorced her. ');">⁶¹</span> Said R. Aha of Difti to Rabina: Are a menstruant and a brother's wife forbidden to marry only during the lifetime of the man who caused their prohibition but permitted after that?<span class="x" onmousemove="('comment',' When the man died. ');">⁶²</span> With a menstruant, surely,

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