(Mishnah): If one had Bi'ah with his mother, he is liable for his mother and for his father's wife (this will be explained);

R. Yehudah says, he is liable only for his mother.

If one had Bi'ah with his father's wife, he is liable for Eshes Av and Eshes Ish, whether in the father's lifetime or after the father's death, whether she was Arusah or Nesu'ah [to his father];

If one had Bi'ah with Kalaso (his daughter-in-law), he is liable for Kalaso, and for Eshes Ish, whether in the son's lifetime or after his son's death, whether she was Arusah or Nesu'ah.

(Gemara) Question: Which Lav forbids Bi'ah with one's mother? "Ervas Imcha Lo Segaleh";

What is the source for Kares? "Ki Kol Asher Ya'aseh mi'Kol ha'To'evos ha'Elu v'Nichresu ha'Nefashos mi'Kerev Amam."

Which Lav forbids Bi'ah with one's father's wife? "Ervas Eshes Avicha Lo Segaleh";

What is the source for Kares? "Ki Kol Asher Ya'aseh..."

What is the source for punishment (Misah)? "V'Ish Asher Yishkav Es Eshes Aviv Ervas Aviv Gilah Mos Yumasu..."

Which Lav forbids Bi'ah with one's daughter-in-law? "Ervas Kalascha Lo Segaleh";

What is the source for Kares? "Ki Kol Asher Ya'aseh mi'Kol ha'To'evos ha'Elu v'Nichresu";

What is the source for punishment? "V'Ish Asher Yishkav Es Kalaso [Mos Yumsu]."

Question: [Our Mishnah] taught here [that he is liable for his mother and for his father's wife], and it was taught in Kerisus. It is fine that it was taught in Kerisus, for he brings a Korban and brings another Korban. Can we say that [it was taught here] in Sanhedrin that he is stoned, and stoned again?!

Answer (R. Yudan, the father of R. Masnei): It was said regarding Hasra'ah. If they warned for Eshes Av, he is stricken (i.e. killed). If they warned for his mother, he is stricken.

Question: [It should teach also that] they can warn for Eshes Ish! (This question is unlike R. Yosi below, who holds that one is never liable for his mother for Eshes Ish.)

Answer (R. Avin): The case is, she is single (her husband died).

Opinion #1: There [in Bavel], they explained R. Yehudah [in our Mishnah. He] says that if his mother was not proper for his father, he is liable only once. (He holds that when a Lav forbids Bi'ah, there is no Kidushin.) This implies that if his mother was proper for his father, he is liable twice! (KORBAN HA'EDAH)

Opinion #2 (R. Avahu citing R. Yochanan): Whether she was proper for his father, or not proper for his father, he is liable only once. (He explains R. Yehudah's opinion.)

R. Yochanan learns from "Imcha Hi" - you obligate him [only] for his mother. The entire Parshah is attributed to his mother.

Question (R. Bun bar Chiyah, to R. Zeira): Why did R. Yochanan mention [that he is liable for] his mother, and abandoned his father's wife?

Answer (R. Zeira): He holds like R. Yishmael. R. Yishmael expounds "Ervas Avicha" to discuss [relations with] a male. (This verse does not discuss the father's wife. The next verse explicitly discusses it.)

Question: Is his father not included in a male?! (He is Chayav Misah and Kares for any male!)

Answer: [The verse] obligates two [Korbanos if he was Shogeg]. A Beraisa teaches that one who had Bi'ah with his father is liable twice.

Question: (The first Mishnah in Kerisus lists 36 Aveiros of Kares. One's father is not among them.) It should teach 37 Kerisus in the Torah!

Answer (R. Mana): Everything due to [Bi'ah of a male with] a male is counted as one.

Ervas Eshes Avicha discusses the father's wife. Ervas Imecha is his mother who is his father's wife. What is the source for his mother who is not his father's wife? "Imcha Hi Lo Segaleh Ervasah."

Question: What does R. Akiva learn from [Ervas Eshes Avicha]? (He holds that Ervas Avicha in the previous verse already forbids the father's wife!)

Answer: He explains that it teaches about after death.

Question: Does R. Yishmael not hold so (that there is a Lav for her even after death)?!

Answer: "Ervas Avicha Hi" - both in the father's lifetime, and after death.

Question: R. Akiva expounded that Ervas Avicha discusses the father's wife. Ervas Imecha is his mother who is his father's wife. What is the source for his mother who is not his father's wife?

Answer: It says "Imcha Hi Lo Segaleh Ervasah."

Question: How does R. Yishmael expound this? (Ervas Avicha refers to the father. There is no source to distinguish whether or not his mother is his father's wife!)

Answer: He explains that it teaches about after death [of his father].

Question: Does R. Akiva not hold that [we need the verse to equate them]? "Ervas Avicha... Ervas Imecha" - just like your father, in any case [he is forbidden] both for the punishment and for the Lav, also your mother, in any case [she is forbidden] both for the punishment and for the Lav!

Answer: (Above, R. Yochanan explained that R. Yehudah expounds like R. Yishmael. We now retract from this.) It is unreasonable that he expounds like this. Rather, [in our Mishnah] R. Yudah does not hold [that one is liable twice for] his mother who is his father's wife. (He learns this from "Imcha Hi.") He needs to expound "Ervas Avicha... v'Ervas Imecha" - just like [the wife of] your father, in any case [she is forbidden, whether or not she is your mother] both for the punishment and for the Lav, also your mother, in any case (whether or not she your father's wife), both for the punishment and for the Lav.

Inference (R. Zeirah): We learn from a Gezeirah Shavah, even if only one side is Mufneh (written unnecessarily).

Objection (R. Yudan): We could not infer so from [a Drashah of] R. Akiva, for R. Akiva learns from a Gezeirah Shavah even if it is not Mufneh [at all]!

Question (R. Yirmeyah): One who had Bi'ah with is mother - is he is liable for Eshes Ish?

Answer: What is the question? If someone else has Bi'ah with her, he is liable for Eshes Ish? All the more so her son is! (Chidushei R. Meir Simchah Daf 53a - even according to the opinion that a light Isur is not Chal on a severe Isur, if they warned only for Eshes Ish, this is more severe than Imo, since now he can be killed only for Eshes Ish.)

Question (R. Yosi): (We can this refute this Kal v'Chomer!) A woman's step-son - he is liable [for Bi'ah with her] for Eshes Av, and her son is not liable for her for Eshes Av (according to R. Yehudah - he is liable only for his mother)!

(Beraisa): Also for all other Arayos, e.g. his mother-in-law and she is an Eshes Ish, you punish him for his mother-in-law. His daughter-in-law and she is an Eshes Ish, you punish him for his daughter-in-law. His sister and she is an Eshes Ish, you punish him for Eshes Ish;

You cannot evade the severe and punish him for the light, for it was taught that one who had Bi'ah with his sister is liable for his sister, and for the daughter of his father's wife!

R. Yosi bei R. Yudah says, one who had Bi'ah with his sister is liable only for one Isur. The same applies to one who had Bi'ah with his daughter-in-law.

(R. Yirmeyah citing R. Avahu citing R. Yochanan): R. Yosi bei R. Yudah holds like his father R. Yehudah (in our Mishnah). For what does R. Yehudah obligate him? [Only] for the first Isur (Imo). So R. Yosi bei R. Yudah obligates [only] for the first Isur.

Retraction (R. Yirmeyah citing R. Avahu citing R. Yochanan): R. Yosi bei R. Yudah does not hold like his father R. Yehudah. There, he is liable for his mother who is not Eshes Aviv. He is liable for Eshes Aviv who is not Imo. (R. Yosi bei R. Yudah could obligate twice for his mother who is Eshes Aviv);

However, here we find that the daughter of his father's wife, if she is not his sister, he is permitted to her! (There is no separate Isur of Bas Eshes Aviv. The Torah wrote it merely to teach that Achoso applies only when her mother was proper to marry his father; this excludes a daughter through a Shifchah or Nochris - KORBAN HA'EDAH.)