Reference for Yevamot 64:2

תינח היכא דנשא חי ואח"כ נשא מת מגו דאתוסף איסור לגבי אחים אתוסף איסור לגבי דידיה

first and the deceased had married<span class="x" onmousemove="('comment',' The other sister. ');">⁴</span> afterwards, since the prohibition. having been extended in the case of the brothers, had also been extended in his own case.<span class="x" onmousemove="('comment',' V. supra p. 202, n. 9. ');">⁵</span> What extension of the prohibition is there, however, where the deceased had married<span class="x" onmousemove="('comment',' One of the sisters. ');">³</span>

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