You wrote in your Torah: “Peru u-rvu” (Bereishit 1:28; 9:1,7) and you wrote in your Torah “Teach them to your children” (Devarim 11:19). And the intent in both of them is the same, for not for void did You create but rather for settling, and for Your honor You created, formed and also made, in order that we and our descendants and the descendants of all Your people the house of Israel be knowers of Your name and learners of Your Torah…

The Master said: Great is peace between a man and his wife, as the Torah said that the name of the Holy One, Blessed be He, which is written in sanctity, shall be erased on the waters as part of the ritual of a woman suspected by her husband of adultery

Isn’t it taught in a baraita...“And they speak to him”; this phrase teaches that they offer him advice that is appropriate for him.The baraita explains: Appropriate advice means that if he was a young man and she an elderly woman or if he was an elderly man and she a young woman, they say to him: What do you want with a young woman when you are elderly? Or: What do you want with an elderly woman when you are young? Go after your own kind, i.e., a woman of a similar age, and do not place discord in your household that could be caused by marrying a woman of a significantly different age.

Question: Reuven has already fulfilled pirya ve-rivya and is widowed and wants to get married but is afraid of conflict (ketata) between the wife and his children, and therefore he wishes to marry a woman who is known to all not to be argumentative at all, but who is not fertile at all…Response…If he marries a woman who is not argumentative at all he does well, even though she is not fertile at all, and although we rule halachically like rabbi Yehoshua in chapter Ha-ba al yevimto [Yevamot 62b] who said if he had children in his youth…on a Torah level, since he has fulfilled pirya ve-rivya, he is no longer obligated…Still, one should bring a proof that we push it [la-erev] aside to prevent conflict….[a proof would be] that we push aside levirate marriage in favor of chalitza on account of conflict.

Rema: If he has many sons and he fears that if he marries a woman of child bearing age an altercation will come and discord will come between the children and his wife he is permitted to marry a woman who is not capable of bearing children

…On account of fear of conflict, he can desist from the mitzva of pirya ve-rivya…

Similarly, if a couple’s relationship is shaky and there is concern that they will have to divorce, they should avoid pregnancy until their relationship is stable. This permit is generally for the period of six months to a year.

Footnote 14:… Experience shows that birth control in such cases is critical, so that if they must divorce, the pain and harm that it causes for them and for the baby will be minimized.

The Gemara relates that Rabbi Ḥiyya’s sons, Yehuda and Ḥizkiyya, were twins, but one of them was fully developed after nine months of pregnancy and one was fully developed at the beginning of the seventh month, and they were born two months apart. Yehudit, the wife of Rabbi Ḥiyya, had acute birthing pain from these unusual deliveries. She changed her clothes to prevent Rabbi Ḥiyya from recognizing her and came before Rabbi Ḥiyya to ask him a halakhic question. She said: Is a woman commanded to be fruitful and multiply? He said to her: No. She went and drank an infertility potion.Eventually the matter was revealed, and Rabbi Ḥiyya found out about what Yehudit had done. He said to her: If only you had given birth to one more belly for me, i.e., another set of twins. As the Master said: Yehuda and Ḥizkiyya were twin brothers and became prominent Torah scholars, and Pazi and Tavi, Rabbi Ḥiyya’s daughters, were twin sisters, and became the matriarchs of families of distinguished Torah scholars.

Rabbi Chiyya’s wife allowed for the possibility that he would divorce her or marry another in addition to her if he wished. But here and now, there is the edict of Rabbeinu Gershom, so that she is not allowed to drink [a sterilizing potion] against the wishes of her husband, for certainly on account of la-erev he could not be released from the edict of Rabbeinu Gershom…It requires permission from her husband or that she agrees to receive a get from him. And if he does not wish to divorce her or to give her permission, it seems to me that she is not obligated to cause herself pain on account of the halachic subjugation she has to her husband, and this refers to great pain, in accordance with the view of the halachic authority, and it is impossible to lay out all the aspects of this.

And Rabbi Yitzḥak from the school of Rabbi Ami says: When a male comes into the world, his loaf of bread, i.e., his sustenance, comes into his possession. In other words, a male can provide for himself. This is based on the aforementioned interpretation of the word male [zakhar] as an abbreviation of: This is a kar [zeh kar]...when a female comes into the world, nothing, i.e., no sustenance, comes with her. This is derived from the homiletic interpretation of the word female [nekeva] as an abbreviation of the phrase: She comes clean [nekiya ba’a], i.e., empty.

The set interval defining the frequency of a husband’s conjugal obligation to his wife stated in the Torah (see Exodus 21:10), unless the couple stipulated otherwise, varies according to the man’s occupation and proximity to his home: Men of leisure, who do not work, must engage in marital relations every day, laborers must do so twice a week, donkey drivers once a week, camel drivers once every thirty days, and sailors once every six months. This is the statement of Rabbi Eliezer.

§ Rabbi Zeira says that Rav Huna says: For the purchase of an object with which to fulfill a mitzva, one should spend up to one-third. The Gemara asks: To what does this one-third refer? If we say it means that one should spend up to one-third of his estate to perform a mitzva, but if that is so, and if it happened to him that he became obligated in three mitzvot at the same time, should he give his entire estate away in order to fulfill those mitzvot? One is certainly not required to do so. Rather, what Rabbi Zeira said is that for the embellishment of the performance of a mitzva, e.g., to purchase a more beautiful item used in the performance of a mitzva, one should spend up to one-third more than the cost of the standard item used to perform the mitzva...

Rema: Somebody who doesn't have an etrog or some other [objected associated with a] mitzvah whose time will elapse need not dispense much wealth on it

It is difficult for me, is there a price to mitzvot? And how can one say that someone should not purchase a lulav and etrog except for up to such and such an amount, and could they estimate prices for them? And is not a single mitzva important as all of his money? And one can say as long as he does not come to poverty and depending on other people, as they said “someone who squanders [on tzedaka] should not squander more than a fifth [of their funds]” (Ketubot 50b).

A righteous person when he is poor should not think: If I have relations with my wife, perhaps she will conceive from me, and whence will I find a livelihood? This is someone lacking in faith, anyone who thinks thus. For it is God who provides milk in the breasts of a woman for her infant when he emerges from inside her, and they said in Midrash Mechilta: “Whoever has something to eat today and says, what shall I eat tomorrow is lacking in faith.”

So did our sages command, that if he knows himself to still be fit to have children, he should marry a fertile woman if his station is sufficient to provide a livelihood for them, and so said our sages, “in the evening [la-erev] do not rest your hands”…and thus is the halachic ruling.

One who is engaged in a mitzva is exempt from performing another mitzva

Rema: Everyone who is involved in a mitzvah is dispensed from engaging in another mitzvah if one has to make an effort for the other mitzvah. However if he can do both mitzvot without exerting himself, he should do both.

(2) The mitzvah of being fruitful and multiplying is incumbent on the husband and not on his wife. When does a man become obligated to fulfill this mitzvah? From the time he reaches seventeen. If he reaches twenty and has not married, he is considered to have transgressed and negated the observance of this positive commandment. If, however, he is occupied with the study of Torah and absorbed in this endeavor and is hesitant of marrying, lest he be forced to work to support his wife and thus be prevented from studying Torah, he is permitted to delay marriage. For a person who is occupied in the performance of one mitzvah is freed from the obligation to perform another. Surely this applies with regard to the study of Torah.

"And you shall watch over the matzoth": R. Yoshiyah says: Read it not "And you shall watch over the matzoth," but "And you shall watch over the mitzvoth." Just as matzoth are not permitted to become chametz (i.e., to sour), so mitzvah should not be permitted to become chametz, but if the opportunity of a mitzvah presents itself to you, perform it immediately.

We learned in the mishna: If a brother makes his decision dependent upon a brother who is currently a minor, the court does not listen to him...why shouldn’t the court listen to him? Let the court wait, as perhaps he will mature and consummate the levirate marriage. Rather, it would appear that the mishna assumes that consummation by a younger brother is not preferable. The Gemara responds: But even according to your reasoning that ḥalitza performed by an elder brother is preferable, what about the next case in the mishna, where a brother asks to wait until the eldest brother comes from overseas? In that case, as well, the mishna rules: They do not listen to him; but why shouldn’t they listen to him? Let the court wait, as perhaps he will come and at the very least perform ḥalitza. Rather, it is clear that the reason for the mishna’s ruling is that we do not delay the performance of any mitzva; therefore, if one of the brothers is currently unable to perform the mitzva, he is not considered at all. Consequently, no proof can be derived from the mishna.

The entire day is suitable for performance of the mitzva of circumcision; however, the vigilant are early in the performance of mitzvot, and circumcise in the morning. As it is stated with regard to the binding of Isaac: “And Abraham arose early in the morning”

All day long is fit for berit mila, as it is said “And on the eighth day [circumcise the flesh of his foreskin].” But in any case it is proper for the zealous to do it early, in the morning, so that he not appear as neglecting it on account of pity for the boy, and so that he hold fast to the ways of the Avot, about whom it was said in a similar matter, “And Avraham arose early in the morning.”

Repentance itself atones for minor transgressions, forpositive mitzvot...

(6) A man may not neglect the mitzva to be fruitful and multiply unless he already has children...and Beit Hillel say: A male and a female

If, however, he has not fulfilled the mitzvah of being fruitful and multiplying, he is obligated to engage in sexual relations whenever his conjugal duties require, until he fathers children. For this is a positive commandment of the Torah, as [Genesis 1:28] states: "Be fruitful and multiply."...When does a man become obligated to fulfill this mitzvah? From the time he reaches seventeen. If he reaches twenty and has not married, he is considered to have transgressed and negated the observance of this positive commandment.

But the mitzva of procreation is one [mitzva] for his entire life, and once he has fulfilled it, he has discharged his obligation. Therefore, anyone who is delinquent with it, that is a delay of a mitzva and not an abrogation, for if he did it in the end, he fulfilled the mitzva. But nevertheless, since he is commanded from now, he is abrogating fulfillment of the mitzva as is proven from Rambam’s language…

You asked if someone who made an oath not to marry a woman until a given time…since he is not making an oath never to marry, but only until a given time, he is not making an oath to abrogate a mitzva [which could not halachically take effect]? Response: This oath takes effect, for this person is not making an oath to abrogate the mitzva. For it is possible to fulfill both [the oath and the mitzva]. And not only because the time [of the mitzva] is not rushed, for even with a mitzva whose time is rushed, like circumcision on the eighth day, if one swears not to circumcise in the morning until the fourth or fifth halachic hour or swears not to eat matza for the first hour of the night [of Pesach], he can keep his oath by waiting until the time he swore. And how much more so this, where the time is not rushed.

(3) It is incumbent on every man that they should marry a woman at the age of 18...If 20 years go by and he has not taken a wife and he who lets 20 years pass, or he who does not want to marry, the courts can force him to marry in order to fulfill the mitzvah of being fruitful and multiplying...

Rema: In this time, its custom that one does not force in regards to this.

Question: One who sees the new moon on a weekday, and says let’s wait to recite the blessing over its renewal until Motzaei Shabbat, do they act properly or not? Response: It seems that one can make a distinction in the matter. Where the upcoming Motzaei Shabbat is not many nights into the month, like the seventh or eighth of the month, so that even if it is cloudy on Motzaei Shabbat, and two or three or four nights afterwards, there will still be time to recite the beracha before the end of the night of the fifteenth, in this case it is good to wait until Motzaei Shabbat. For Or Zarua wrote: We recite the beracha over the moon only on Motzaei Shabbat, when they [the people] are perfumed and in nice clothing….Whenever it is fitting to doubt lest the mitzva time pass, we do not delay [performing] it, even in order to do it in a more select fashion. And the proof is from that which we learn [Yevamot 39a]…It is proved there, that specifically when it is fitting to be in doubt lest the mitzva [time] pass, then we do not delay it…