Explanation (R. Tam): This is only when the ruling affects him himself, e.g. Yisra;

He needed this ruling, for he married Yishai's daughter, like it says "Asher Ba El Avigayil Bas Nachash";

We say in Bava Basra (14a) that she was the daughter of one who died due to the snake's bad counsel (i.e. because death was decreed on all people after Adam ate from Etz ha'Da'as. Yishai is one of the four who never sinned.)

Support: Similarly, below (98a) regarding a convert who testified about his wife and his seven children, and in Kidushin (70b) regarding the episode with Rav Yehudah...

Whenever we say (that one is not believed unless he taught the teaching before the episode), he needed the teaching for himself.

Distinction: If he does not need the ruling for himself, we heed him, even if he did not teach it before the episode occurred.

Question: According to R. Yehudah, we can ask that we should expound "Mitzri v'Lo Mitzris"!

Answer (Ri): Regarding Amon and Mo'av, the Torah should have written more concisely "Amon and Mo'av";

Therefore, since it rather wrote "Amoni v'Mo'avi", we expound that this comes to exclude Amonis and Mo'avis;

However, regarding Mitzri, it would be longer to write Mitzrayim [so there is no indication that it is to exclude a Mitzris].

Implied question: The Torah wrote Edomi, and not Edom! (We should say that this is to exclude an Edomis!)

Answer: Since it wrote Mitzri, (for consistency) it wrote Edomi (but we do not exclude an Edomis).

Implied question: David himself said this! (How can he learn from a Gezeirah Shavah to a verse that he himself wrote? Maharsha asks that Eisan ha'Ezrachi wrote this Tehilim (89).)

Answer: He said it with Ru'ach ha'Kodesh.

Question: We bring this [Tzad ha'Shavah] of a widow to a Kohen Gadol and a Chalal according to R. Yosi. Even R. Yehudah (who is stringent about a convert's daughter) disagrees!

This is because we can ask like we ask here, that an Aveirah was involved in each of the sources, like it says in Kidushin (78a)!

Strengthening of question: We should have brought [the Tzad ha'Shavah] from which R. Yehudah learns that a male convert's daughter is [a Chalalah,] like a Chalal's daughter! He learns from a Chalal and a Mitzri Rishon, like it says there.

Distinction: However, regarding daughters of converts of other nations, we can say that R. Yosi disagrees with R. Yehudah's Tzad ha'Shavah;

He does not consider it to be a Tzad ha'Shavah that they are unlike most of Kahal [Yisrael], since a convert is permitted to Kahal.

Support: Also Rashi explained so there regarding R. Eliezer ben Yakov, who argues with R. Yehudah.

However, here a Ger Amoni is considered Tzad ha'Shavah, since he may not enter (marry into) the Kahal!

Question: Why doesn't R. Yosi learns from a Chalal and a Mitzri Rishon to disqualify to a Kohen the daughter of an Amoni married to an Amonis, even though she may enter the Kahal?

Answer: R. Yosi holds that since the daughter of a Mitzri Rishon may not enter the Kahal, we should not make a Tzad ha'Shavah from a Pesul to Kehunah and a Pesul to the Kahal to learn from here in general to disqualify to Kehunah.

Suggestion: We should learn that a convert disqualifies through Bi'ah from a Chalal and a Mitzri Rishon!

Now we can make a Tzad ha'Shavah, since we do not come to make a Tzad ha'Shavah from it, from that the daughters are forbidden, this to Kahal and this to Kehunah. Rather, [we come to learn because] they are unlike most of the Kahal!

Rejection #1: A convert is considered to be in (i.e. like) most of the Kahal according to Rabanan, like I explained.

Rejection #2: We cannot learn from them, for their children are Pasul, to a convert, whose daughter is Kesherah!

Question: If one was Machazir Gerushaso, or a Yevamah l'Shuk, we should learn that they disqualify through their Bi'ah from a Chalal and a Mitzri Rishon!

Answer: We must say like we explained above (15b) that Rabanan do not learn from an Isur Kehunah to make a Chalalah, since Chalalah is only from Isurei Kehunah, even through a Tzad ha'Shavah from elsewhere and from a Pesul Kehunah;

R. Yehudah surely learns from a Tzad ha'Shavah even to disqualify through his Bi'ah, like he says in Kidushin (78a).

Question (Ri): How do we learn above (45a) from a Kal va'Chomer from a widow [to a Kohen Gadol] that if a Nochri or slave has Bi'ah with a Yisraelis, the child is tainted?

According to R. Yochanan, we can say that the daughter of a Ger Amoni who married a Bas Yisrael refutes it! The Isur applies to everyone, and his daughter is Kosher to Kehunah!

Partial answer: According to R. Shimon ben Gamliel, who says above (69a) that a Ger Amoni does not disqualify through Bi'ah, this is fine;

However, according to the first Tana and R. Yosi, this is difficult!

Distinction: However, we cannot ask that a Mitzri Sheni refutes this, for he is forbidden only with an Aseh.

Question (R. Moshe Kohen): Above (69a), it connotes that all agree that the daughter of an Amoni or Mitzri Sheni is Kesherah to Kehunah;

We asked what the first Tana and R. Yosi argue about, and R. Yochanan said that they argue about a Mitzri Sheni... [We concluded] "this excludes a Mitzri Sheni, for his children are not Pesulim like a Kohen Gadol's children from a widow."

Regarding a Ger Amoni, it says [there] that not all his children are Pesulim [like a Kohen Gadol's children from a widow]. This implies that his daughter is Kosher to Kehunah!

Answer (Ri): R. Yochanan taught the Sugya above. He says here that she is Kesherah;

However, Reish Lakish, who disqualifies here, will say that the first Tana disqualifies there because his children are Pasul;

He does not explain the first Tana like R. Yochanan did, that just like a Kohen Gadol's Bi'ah is forbidden... for if so, this would connote that he agrees to R. Yosi that the seed of a Mitzri Sheni is not Pasul [just they argue about what determines whose Bi'ah disqualifies];

Rather, he (Reish Lakish) would have said also according to the first Tana, just like a Kohen Gadol's seed from a widow is Pasul...

Note: The first Tana and R. Yosi agree that one's Bi'ah disqualifies if at least some of his seed is Pasul. They argue about a Mitzri Sheni's daughter.

He (the first Tana, according to Reish Lakish) holds that the daughter of a Ger Amoni or of a Mitzri Sheni [shows that at least some of] his seed is Pasul;

R. Yosi says "anyone whose seed is Pasul...", and he excludes a Mitzri Sheni. He adopted these words according to himself. (He holds that all of his seed is Kosher.)

Question: What would be the source to disqualify her?

Suggestion: We learn from a Chalal and a widow [to a Kohen Gadol].

Rejection: They have an Isur Lav. We cannot learn to an Mitzri, which is an Aseh!

Answer (R. Yitzchak): We learn from [a widow, and] a Chalal of Chayavei Aseh, e.g. a Be'ulah to a Kohen Gadol, according to R. Eliezer ben Yakov, who says that there is a Chalal from Chayavei Aseh.

Question #1: We discuss according to R. Yochanan. According to him, we find a Mamzer without Kares. He holds that if a Nochri or slave has Bi'ah with a Yisraelis, the child is a Mamzer!

Question #2: Also, he could have said "we cannot learn from the Tzad ha'Shavah, which is a Lav, to a Mitzri, which is only an Aseh!"

Question (Rivam): In any case, we can ask that the Tzad ha'Shavah is a Lav;

Even regarding a Chalal from Chayavei Aseh, there is a Lav of "Chalalah Lo Yikach"!

Answer (Rivam): Perhaps regarding a Chalal from Chayavei Aseh, there is no Lav. There is only an Aseh for a Kohen who has Bi'ah with her.

Explanation: He does not mean a Halachah (tradition) from Moshe from Sinai. If he did, why would R. Yehudah disagree?!

Rather, he means 'I say a Halachah'; I received so from my Rebbeyim.