(Mishnah): Reuven died, and Shimon did Yibum with Chanah. Levi (another brother) was born, and Shimon died. Chanah is exempt, for she is Eshes Achiv she'Lo Hayah b'Olamo. Leah (Shimon's other wife) is exempt, because she is Chanah's Tzarah.

If Shimon gave a Ma'amar and died, Leah does Chalitzah but not Yibum;

R. Shimon says, Levi may do Yibum or Chalitzah with either woman.

(Gemara) Question #1: R. Shimon says, [it is a Safek whether] Ma'amar acquires or does not acquire, and you say so, [in the Seifa] he permits Yibum with Ba'alas (the one who received) ha'Ma'amar?!

You should be concerned lest Ma'amar does not acquire, and he is liable for Eshes Achiv she'Lo Hayah b'Olamo!

Question #2: [Why does he permit] Chalitzah with Ba'alas ha'Ma'amar? You should be concerned lest Ma'amar does not acquire, and [only] the second [widow] is Zekukah to him (so Chalitzah of Ba'alas ha'Ma'amar did nothing)!

Answer (to both questions): R. Shimon refers to the Reisha (if Shimon did Yibum, Levi was born, and then Shimon died, Levi may do Yibum or Chalitzah with either woman).

(R. Yochanan): R. Shimon agrees in the first case [the previous Mishnah, in which Levi was born and then Shimon did Yibum].

A Beraisa was found that says that also this (the first case) is an argument (R. Shimon permits Yibum).

Question: [According to R. Yochanan,] what is the difference [between the first case and the second, i.e. our Mishnah]?

Answer: In the first case, he came [to the world] and found [his Yevamah] forbidden. In the second, he came and found her permitted.

Question (R. Yochanan): If [one was born after his mother was widowed or divorced,] and he found Eshes Aviv married l'Shuk (to another man), what would R. Shimon say? Because he found her permitted (i.e. when he was born, she was not Eshes Aviv, rather, another's wife), is she permitted (after she is widowed or divorced from her current husband)?!

Answer: R. Shimon said [since he found her permitted...] only regarding brothers [since the Isur goes away through Yibum].

Question (R. Yakov bar Acha citing Reish Lakish): If one found his maternal brother's wife married to his paternal brother (i.e. she did Yibum), what would R. Shimon say? Because he found her permitted, is she permitted (to do Yibum if her husband died)?

Answer: R. Shimon said only regarding paternal brothers. (Do not say that since the Isur of a paternal brother's wife was permitted, also the Isur of a maternal brother's wife was permitted.)

Question (R. Yudan): The Tzarah of Achos Imo that he found her married to his paternal brother - because he found her permitted, is she permitted? (A Tzarah is forbidden only due to Eshes Ach, which was permitted through Yibum. Or, perhaps R. Shimon permits only when she would have been permitted to him had he been born the first time she fell to Yibum. Here, had he been born then, she would have been forbidden due to Tzaras Ervah!)

Question (R. Avin): If [a brother was born after the Yevamah did Yibum and was] divorced, [and she remarried the Yavam] and she was widowed, [what is the law? Is she forbidden, for he found her without Zikas Yibum? Or, since Eshes Ach was permitted, when she falls to Yibum, she is permitted? We explained this like R. MEIR SIMCHAH.]