Reference for Yevamot 63:4

אמר רבא נתן גט למאמרו הותרה צרתה אבל היא אסורה דמחלפה בבעלת גט

Others say that Raba said: If he<span class="x" onmousemove="('comment',' V. note 6. ');">¹¹</span> gave a letter of divorce in respect of his ma'amar even she herself becomes permitted.<span class="x" onmousemove="('comment',' And she is thus subject to the third brother as the widow of the first. ');">¹²</span> What is the reason? — Because what he has done to her he has taken back.<span class="x" onmousemove="('comment',' The ma'amar by which he bound her he has himself annulled. ');">¹³</span>

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