(Mishnah): Reuven, Shimon and Levi (brothers) were married to Rachel and Leah (sisters) and Esther (an unrelated woman), respectively. Reuven died. Levi did Yibum, then he died. Rachel is exempt (from Yibum and Chalitzah) because she is Achos Ishto to Shimon (his wife's sister). Esther is exempt because she is Tzaras [Ervah].

If Levi [did not do Yibum, rather, he] gave a Ma'amar and then died, Esther does Chalitzah, but not Yibum.

(Gemara): Both Rabanan and R. Shimon agree [in our Mishnah];

According to Rabanan, the side that Ma'amar acquires, correspondingly is forbidden in the Tzarah. The side that Ma'amar did not acquire, correspondingly is permitted in the Tzarah. Therefore, she does Chalitzah and not Yibum;

According to R. Shimon, if Ma'amar acquires, both are forbidden (one is Achos Ishto, and the other is her Tzarah). If Ma'amar did not acquire, the first (Rachel) is forbidden (due to Achos Ishto), and the second is permitted (she fell from a different brother). Due to Safek, she does Chalitzah and not Yibum.

(Mishnah): Reuven and Shimon were married to Rachel and Leah (sisters) and Levi was married to Esther. Levi died. Reuven did Yibum, then he died. Rachel is exempt because she is Shimon's Achos Ishto; Esther is exempt because she is Rachel's Tzarah.

Had Reuven [not done Yibum, but] gave a Ma'amar and then died, Esther would do Chalitzah, but not Yibum.

(Gemara): Both Rabanan and R. Shimon agree [in our Mishnah].

(Mishnah): Reuven and Shimon were married to Rachel and Leah (sisters) and Levi was married to Esther. Reuven died. Levi did Yibum. Leah died, then Levi died. Rachel is forever forbidden to the Yavam, since she was once forbidden.

(Gemara - R. Avina): This is like R. Yosi said in the name of R. Yochanan - the Isur of sisters who are Yevamos is unlike the Isur of sisters who are not Yevamos. (If they are not Yevamos, after one's wife dies, he may marry her sister. If they are Yevamos, like in our Mishnah, his wife's sister is forbidden even after his wife dies.)

(Mishnah): Reuven and Shimon were married to Rachel and Leah (sisters) and Levi was married to Esther. Reuven divorced Rachel, Levi died, Reuven did Yibum, then he died -

About this they said 'in all cases that [an Ervah] died, did Mi'un, was divorced, or was found to be an Ailonis, the Tzaros are permitted'.

(Gemara - Mishnah): He divorced her...

(R. Chagai citing R. Ze'ira): This is not only if he divorced her, and later did Yibum. Rather, it is even if he did Yibum, and afterwards divorced.

This is what was taught, if [an Ervah] died or was divorced, her Tzaros are permitted.

(R. Yudan): Even R. Lazar (who holds that even when the cause is Batel, the Isur is in its place) agrees [to our Mishnah].

Support (R. Yosah): This is proper. If one had children, and they died, and afterwards he died, is his wife not Zekukah to Yibum?! (We do not forbid her, because initially he had children!)

There, [the Torah exempts] if he had children at the time of death. Here, [Tzaras Ervah is exempt] if she is a Tzarah at the time of death.