(Mishnah): The following relatives [are disqualified from testifying]: a brother, a paternal or maternal uncle, a sister's husband, the husband of a paternal or maternal aunt, a step-father, a father-in- law, and a Gis (the husband of his wife's sister):

Also, their sons (i.e. of these relatives) and their Chasanim (son-in-laws) are disqualified, and a step-child alone (is disqualified).

R. Yosi says, R. Akiva taught this. Mishnah Rishonah disqualified only an uncle, cousin, and anyone proper to inherit him (i.e. paternal relatives), and anyone who was related at the time (that he saw testimony or comes to testify);

If he was related but became distanced, he is Kosher.

R. Yehudah says, even if his daughter died and he has children from her, he is a relative [to them].

(Gemara) Question: Since his brother was taught, why did it need to teach his father's brother? (The Mishnah taught that a brother is Pasul, and also his son (a nephew to his uncle!)

Answer: This teaches the son and Chasan of the Chasan of his father's brother. (Hagahos R. Dinar - we infer the repetition (and other repetitions asked below) that the first generation is Pasul to the third, and even through marriages.)

Question: Since it taught his father's brother, why did it need to teach his mother's brother? (Both of them are a first generation with a second - KORBAN HA'EDAH.)

Answer: This teaches the son and Chasan of the Chasan of his mother's brother.

Question: Since it taught [David's] sister's husband, (he is forbidden to David and his son, why did it need to teach the husband of his father's sister? (That is the sister's husband's relation to David's son!)

Answer: This teaches the son and Chasan of the Chasan of his father's sister's husband.

Question: Since it taught his father' sister's husband, why did it need to teach the husband of his mother's sister? (We already learned that a man is like his wife!)

Answer: This teaches the son and Chasan of the Chasan of his mother's sister's husband. (I.e. maternal relatives are like paternal, even to make a man like his wife.)

(Mishnah): And a step-child alone. (This implies that a step-daughter's husband is Kosher.)

Question (Rav): If the Chasan of his mother-in-law is forbidden, all the more so the husband of his step-daughter! (E.g. if Yakov married Rachel, and each of them has a daughter from a previous marriage, and Reuven and Shimon married those daughters, Shimon is the Chasan of Reuven's mother-in-law, and they are Pasul to each other. All the more so Shimon is Pasul to Yakov!

Answer: The case is, [Rachel] has sons and Chasanim from [Yakov. Then the Chasan of his mother-in-law is his wife's sister' husband (Giso), but the husband of his step-daughter is Kosher.]