Yevamos 4:7 - 4:8

הרי הוא כחד מן האחין – and he did not lose his portion because he performed Halitzah for you might think that I would say that he would be fined for since he caused her to lose from [having] levirate marriage for she was disqualified on [his] brothers.

זכה בנכסי אחיו – and even if he would divorced her on the morrow, for the All-Merciful one stated (Deuteronomy 25:6): “[The first son that she bears] shall be accounted to the [dead] brother,” and he has stood up [and performed his duty].

נכסים של אב – as it is written (Deuteronomy 25:6): “The first son [that she bears shall be accounted to the dead brother],” just he doesn’t have a first-born son during the life of the father, even the levir doesn’t have it during the lifetime of the father, and such is the Halakha but rather, a man who marries his sister-in-law takes possession of the property of his brother, and even in the place of the father.

אסור בקרובותיה – as if she is his wife and all of the female relations that are forbidden [to him] on account of the woman is completely his wife, are forbidden for Halitzah according to the Rabbis.

בזמן שהיא קיימת – it refers to her sister, and not to the rest of the women forbidden on account of consanguinity.

מותר אדם בקרובת צרת חלוצתו – and we don’t say that the rival/co-wife is like the woman who has undergone Halitzah, that he would be forbidden with the sister of the rival/co-wife of the woman with whom he performed Halitzah, like he is prohibited [to be] with the sister of the woman with whom he performed Halitzah.

ואסור בצרת קרובת חלוצתו – Reuven who performed Halitzah with Leah and Rachel is married to a foreign (i.e. unrelated Jewish) man, and she has a rival/co-wife, and the foreign (i.e., unrelated Jewish) man died, that rival/co-wife is prohibited to Reuven. And the reason for this is at the time when Leah had the Halitzah ceremony performed, she brought Rachel her sister with her to the Jewish court, and the entire world doesn’t know to which of them had Halitzah and there are those who think that to Rachel was peformed Halitzah, and when the rival/co-wife of Rachel gets married, that is the rival/co-wife of the the relative of his Halitzah, they say that the rival/co-wife of his Halitzah married, and they think that Rachl and her rival/co-wife were the wives of his brother, because he did Halitzah to Rachel. But, the sister-in-law does not bring her rival/co-wife with her at the time that she has the Halitzah ceremony performed, therefore, when the sister of her rival/co-wife gets married, we don’t say that it the sister of the woman who had Halitzah that married.

וכן המגרש את אשתו וכו' – In the Gemara (Tractate Yevamot 41a), it raises the question and similarly, you might think, but rather, I would say, that a man who divorces his wife, etc., that the sister of the divorced woman from the words of the Torah, and therefore is exempt from Halitzah and from levirate marriage, but the sister of the woman who underwent Halitzah, according to the words of the Scribes/Soferim, so therefore, she engages in Halitzah does not engage in levirate marriage.