It says "Ervas Eshes Achicha Lo Segaleh" - this connotes both the wife of his paternal brother and the wife of his maternal brother, both the wife of his brother that was in his world (they lived together), and Eshes Achiv she'Lo Hayah b'Olamo (he died before his brother was born), both in [his brother's] lifetime (e.g. he divorced his wife) and after death, whether [his brother] had children or had no children;

Suggestion: This Isur was totally permitted through Yibum. Perhaps it is permitted in every case!

Rejection: It says here "Ki Yeshvu Achim Yachdav", and it says there "Shneim Asar Avadecha Achim Anachnu" - just like there, it discusses paternal brothers, also here it discusses paternal brothers.

"Yachdav" excludes Eshes Achiv she'Lo Hayah b'Olamo.

"U'Mes Echad Mehem" - but in his lifetime, e.g. if he divorced her, even if he died [afterwards], she is exempt (HA'GAON RAV C. KANIEVSKY, SHLITA. She is not called Eshes ha'Mes.)

"U'Ven Ein Lo" - but if he has a son, she is exempt.

It says "Ki Kol Asher Ya'aseh mi'Kol ha'To'evos ha'Eleh v'Nichresu" - Eshes Achiv was among the Arayos, and it was totally permitted through Yibum;

Suggestion: Perhaps even the other Arayos are totally permitted through Yibum!

Rejection (R. Ze'ira citing R. Yosi ben Chaninah): We learn from a Gezeirah Shavah "Aleha-Aleha". [It says here "v'Ishah El Achosah Lo Sikach Litzror Legalos Ervasah Aleha b'Chayehah", and it says there] "Yevamah Yavo Aleha". Just like Aleha there is a paternal brother, also here it is a paternal brother [in a case of Yibum, and the Torah says Lo Sikach. Similarly, all Arayos are forbidden even in a case of Yibum.]

R. Binyamin bar Gidal and R. Acha were sitting. R. Acha said this Drashah of R. Yosi ben Chaninah.

Question (R. Binyamin bar Gidal): Perhaps just like Aleha there (Achos Ishto) discusses when she is not a Yevamah, also Aleha here discusses when she is not a Yevamah! (He objected to the wording 'also here it is a paternal brother.' He should have said 'a case of Yibum'!)

Objection (R. Acha): The Torah says that she is a Yevamah, and you say that she is not a Yevamah?!

Counter-Objection (R. Binyamin bar Gidal): The Torah says that [Achos Ishto] is not a Yevamah, and you say that she is a Yevamah?!

R. Acha was upset with [R. Binyamin].

(R. Yosi): R. Binyamin does not argue [with the Drashah], just he was adamant about the wording that [R. Acha] heard from his Rebbi (R. Yosi ben Chaninah. We explained this based on MEICHAL HA'MAYIM.)

Question: How do we learn [to forbid other Arayos to do Yibum]?

Answer: "Yevamah Yavo Aleha" - just like Aleha said there refers to a Yevamah, also Aleha said here is even his Yavam, and the Torah said "v'Ishah El Achosah Lo Sikach";

Question: I know only her (Achos Ishto). What is the source for her Tzarah?

Answer: "Litzror" - her Tzarah and the Tzarah of her Tzarah do not [do Yibum or Chalitzah].