Reference for Yevamot 109:11

יש לה בנים לאחר מיתת בעלה לא צריכא קרא מדאמר רחמנא שאין לה בנים מותרת הא יש לה בנים אסורה

whether he is paternal or only maternal. Might it not be suggested that the one as well as the other<span class="x" onmousemove="('comment',' The two sections of the verse cited. ');">²²</span> speaks of the wife of a paternal brother, the one referring to a brother's wife who had children during the lifetime of her husband,<span class="x" onmousemove="('comment',' Who divorced her. ');">²³</span>

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