(Beraisa): "Uv'Nucho Yomar Shuvah Hash-m Rivevos Alfei Yisrael" teaches that the Shechinah does not rest on less than 22,000 Yisraelim (two Revavos and two thousands);

If there were 21,999 Yisraelim, and a man did not engage in procreation, he caused the Shechinah to depart from Yisrael!

Aba Chanan says, he (one who does not engage in procreation) is Chayav Misah. "They (Nadav and Avihu) did not have children" - had they had children, they would not have died;

Others say, he causes the Divine Presence to depart from Yisrael (through reducing the population) - "Lihyos Lecha l'Eilokim ul'Zar'acha Acharecha";

When you have children, the Shechinah dwells. When you do not, will it dwell on sticks and rocks?!

(Mishnah): If a man married a woman and she did not give birth in 10 years, he may not neglect Peru u'Rvu;

If he divorced her, she may marry another man, and the latter man may keep her for 10 years without children;

If she miscarried, we count 10 years from the miscarriage.

(Gemara - Beraisa): If a man married a woman and she did not give birth in 10 years, he must divorce her and pay a Kesuvah. Perhaps (she is not sterile, just) he did not merit to have children through her;

We have no proof from the Torah, but there is a hint - "At the end of 10 years that Avram lived in Eretz Kena'an (he married Hagar)". This teaches that time in Chutz la'Aretz does not count (after one comes to Eretz Yisrael);

Therefore (since we rely on the merit of Eretz Yisrael, we also rely on excuses why she did not conceive until now, e.g.) if either of them was sick, or if both were in jail, this does not count towards the 10 years. (Me'iri - it is possible, but not normal, for them to have relations in jail. All the more so, if only one of them was in jail, the time does not count!)

Question (Rava): Why don't we learn from Yitzchak? "Yitzchak was 40 years old when he married Rivkah", and "He was 60 when she gave birth"!

Answer (Rav Nachman): Yitzchak was sterile.

Question (Rava): Also Avraham was sterile!

Answer (Rav Nachman): The latter verse about Yitzchak is needed for R. Chiya bar Aba's teaching (but the verse about Avram is solely to hint to the law of 10 years).

(R. Chiya bar Aba): The years of Yishmael were counted in order to reveal about Yakov's years (his age when he went to Lavan - see Rashi here and Bereishis 28:9).

(R. Yitzchak): Yitzchak was sterile - "Yitzchak prayed to Hash-m Nochach (opposite, in the presence of) his wife";

It does not say for his wife, rather, opposite her. This teaches that they were both sterile (and requesting mercy).

Question: If both prayed, why does it say "Hash-m hearkened to him"? It should say 'to them'!

Answer: The prayer of a Tzadik Ben Tzadik is much greater than the prayer of a Tzadik whose father is evil.

(R. Yitzchak): The Avos were sterile, because Hash-m desires the prayers of Tzadikim.

(R. Yitzchak): The prayers of Tzadikim are compared to a pitchfork;

Just like a pitchfork moves grain from one place to another, also prayers of Tzadikim switch the Midos that Hash-m uses, from the Midah of anger to the Midah of mercy.

(R. Ami): Avraham and Sarah were Tumtumim (their genitals were initially covered). "Look to the rock from which you were carved, and to the hammer from which your opening was made." "Look to Avraham and Sarah who gave birth to you."

(Rav Nachman): Sarah was an Ailonis. "Sarai was sterile, she had no child" - she lacked even the housing (womb) for a child.

(Rav): The Mishnah applied to the early generations, who lived long. Nowadays one may wait two and a half years, the time of three pregnancies.

(Rabah, citing Rav Nachman): One may wait three years, corresponding to three Pekidos (decrees of prophecy);

On Rosh Hashanah, pregnancy was decreed for Sarah, Rachel and Chanah.

Objection (Rabah): These laws are incorrect!

Rebbi codified our Mishnah, and peoples' years were already shortened in David's days - "The days of our years are 70 years"!

Question: The Beraisa says that (he must pay a Kesuvah, for) perhaps he did not merit to have children through her. Perhaps she did not merit to conceive from him!

Answer: Since she is not commanded about Peru u'Rvu, she would not be punished through inability to fulfill it.

Objection: Rabanan told R. Aba bar Zavda that he should marry and have children, and he replied that had he merited, he would have had children through his first wife!

Answer: He dispelled them off with empty words. Really, he became sterile through (delaying urinating during) Rav Huna's class.

Rav Gidal, R. Chelbo, and Rav Sheshes became sterile through Rav Huna's class.

Rav Acha bar Yakov was seized by a sickness (from withholding urine, which can cause sterility). They hung him from a tree, and green matter exuded from him.

Rav Acha bar Yakov: I was among 60 elders who attended Rav Huna's class. All became sterile except for myself - Chachmah gives life to those who have it! (He knew how to cure himself.)

(Mishnah): If he divorced her, she may remarry...

Inference: She may marry a second man, but not a third. Our Mishnah is like Rebbi:

(Beraisa #1 - Rebbi): If a woman circumcised two of her sons and they died, she should not circumcise her third son;

R. Shimon ben Gamliel says, she circumcises the third, but not a fourth.

Another Beraisa (#2) switches the opinions.

Question: Which was taught later?

Answer (R. Chiya bar Aba): There was a case of four sisters in Tzipori. Three circumcised their sons, and all died. The fourth came to R. Shimon ben Gamliel. He told her not to circumcise her son. (This supports Beraisa #1; it was taught later).

Objection: Perhaps he would have told also the third not to circumcise!

Question: If so, what do we learn from R. Chiya's testimony?

Answer: He teaches that a Chazakah may be established through sisters.

(Rava): Now that we see that sisters make a Chazakah, a man should not marry a woman from a family of epileptics or lepers;

This only applies if there are three in the family.

Question: What was the conclusion?

Answer (R. Yitzchak bar Yosef): A case occurred in which two sons of a woman died through circumcision. She came to R. Yochanan on Yom Kipur that fell on Shabbos to ask about her third son. He told her to circumcise him.

Abaye: You permit an Isur and a danger!

Abaye relied on this and married Chomah, who had been widowed twice; Abaye also died in her lifetime.

Question (Rava): Does anyone jeopardize his life like this?!

Objection #1: Abaye himself said that we can rely on Avin, but not on Yitzchak!

Avin reviews his learning, but Yitzchak does not!

Objection #2: They argue about circumcision. Do they argue about marriage?!

Answer to Objection #2: Yes!

(Beraisa - Rebbi): If she married a man, and he died; a second man, and he died; she may not marry again;

R. Shimon ben Gamliel says, she may marry a third man, but not a fourth.

Question: Granted, regarding circumcision, some families have weak blood and others have strong blood;

However, why should a woman have a Chazakah that her husbands will die?

Answer #1 (R. Mordecai): Bi'ah with her causes her husband to die.

Answer #2 (Rav Ashi): Her Mazal causes him to die.

The difference between these answers is if her husband died during Kidushin, or her husband fell from the roof (these can be attributed only to Mazal).

Rav Yosef brei d'Rava: I asked Rav Yosef if the Halachah follows Rebbi; he said that yes; another time, I asked if the Halachah follows R. Shimon ben Gamliel, and he said yes!

Was he mocking me?

Rava: No. Regarding marriage and lashes, the Stam Mishnah is like Rebbi. Regarding Vestos (expected menstrual periods) and an ox Mu'ad (established) to gore, the Stam Mishnah is like R. Shimon ben Gamliel.

We taught about marriage above (she may marry a second time, but not a third).

Lashes - (Mishnah): If one was lashed twice (for Chayavei Kerisos), Beis Din locks him in a cell and feeds him barley, which causes his stomach to burst.

Vestos - (Mishnah): A woman establishes a Veses after three periods (at the time of the Veses). She only uproots a Veses after three times when she does not have a period at the time of the Veses.

A Mu'ad ox - (Mishnah): An ox is established to be Mu'ad after three times.