The Mitzvah to Have Children (Pru Urvu)

(6) A man may not neglect the mitzva to be fruitful and multiply unless he already has children. Beit Shammai say: One fulfills this mitzva with two males, and Beit Hillel say: A male and a female, as it is stated: “Male and female He created them” (Genesis 5:2).

§ The mishna states that Beit Shammai say that one fulfills the mitzva to be fruitful and multiply when he has two males. The Gemara asks: What is the reason of Beit Shammai? The Gemara answers: We learn this from Moses as it is written: “The sons of Moses, Gershom and Eliezer” (I Chronicles 23:15). Since Moses did not have any other children, two sons must be sufficient to fulfill the mitzva. And the reason of Beit Hillel is that we learn from the creation of the world, as mankind was created male and female.

(5) Once a man has had a son and a daughter, he has fulfilled the obligation to be fruitful and multiply.

How many children must one have to fulfill the Mitzvah? A male and female. As the verse states "He created them; male and female".

The baraita states: If one of a man’s children died or was discovered to be a eunuch, the father has not fulfilled the mitzva to be fruitful and multiply.

(5) Once a man has had a son and a daughter, he has fulfilled the obligation to be fruitful and multiply. And a ben siris (castrated son) and a nekivah ayalonit (girl who doesn't have the ability to give birth) do not count.

From it (the law about the son) we extrapolate to a female who is unable to give birth too.

(6) If a man and a woman bear children and they die, and they leave behind sons, the man dies having fulfilled the mitzvah to be fruitful and multiply.

Even though one has fulfilled the commandment of Pru Urvu he is commanded by the Rabbis to continue to procreate as long as he has the strength. For one who adds one soul to the Jewish people it is as if if he has built a world.

The world was created only for procreation, as it is stated: “He did not create it to be a waste; He formed it to be inhabited” (Isaiah 45:18).

The purpose of the commandment to procreate is so that the birth of the body be a prelude for the acquisition of the intelligent essence of man. It is this intelligent essence which enables him to serve his Creator, were it not for that, man’s superiority to the animals would be nil.
The purpose of all Israelites is dedication for the sake of His Holy Name, in order to serve G’d.
Unlike those who conceive children so that they may eat and drink like animals.

Rather our purpose and intent must be for his name.

(2) It is from the roots of this commandment (i.e the reason behind this commandment) that the world should be settled (Gittin 41b) because God wants the world to be settled, as it says (Isaiah 45:18), "I did not create it for naught, but [rather] formed it for habitation." This is a great commandment, through which all the commandments are observed, as [the Torah] was given to people and not to the ministering angels (Berakhot 25b).

Anyone who doesn't engage in being fruitful and multiplying is as if he spills blood, and lessens the appearance, and causes the divine presence to depart from Israel.

(2) One can only sell a sefer Torah in order to learn Torah or marry a woman.

(1) The commandment of procreation: [Parshat] Bereshit has one positive commandment and that is the commandment of procreation, as it is stated (Genesis 1:28), "And God blessed them and told them to procreate."

(1) That is that He commanded us to be fruitful and multiply, with the intention of preserving the species. And that is the commandment of piryah verivyah. And that is His, may He be exalted, saying, "And you, be fruitful and multiply" (Genesis 9:7).

And After the flood Hashem blessed Noach and his sons.....

Even though G-D already instructed Adam about procreating, that was only a blessing and not a command.

The commandment to be fruitful and multiply that we find in Genesis 9,7, is a repetition of the same commandment already recorded in פרשת בראשית in 1,28: "G–d said to them: "Be fruitful and multiply, etc".

GEMARA: From where are these matters derived, that a woman is not obligated in the mitzva to be fruitful and multiply? Rabbi Ile’a said in the name of Rabbi Elazar, son of Rabbi Shimon: The verse states: “Be fruitful and multiply, and fill the land and conquer it” (Genesis 1:28). It is the manner of a man to conquer and it is not the manner of a woman to conquer. Consequently, it is evident that the entire command, including the mitzva to be fruitful and multiply, was given only to men and not to women. Rav Yosef said: The proof is from here: “And God said to him: I am God Almighty, be fruitful and multiply [perei urvei]” (Genesis 35:11), which is in singular, and it does not state: Be fruitful and multiply [peru urvu] in the plural.

(13) A woman is not obligated in the mitzvah of being fruitful and multiplying.

The statement of Rav Yosef was stated, that it is preferable that the betrothal be performed without an agent because it's greater when a mitzvah is done yourself, it was stated with regard to the latter clause of the mishna: A woman can become betrothed by herself or by means of her agent.

It is taught in a mishna (Gittin 41a): One who is half-slave half-freeman, e.g., a slave who had been jointly owned by two people, one of whom emancipated him, serves his master one day and himself one day; this is the statement of Beit Hillel. Beit Shammai say: You have remedied the situation of his master, who benefits fully from all his rights to the slave, but you have not remedied his own situation. He cannot marry a maidservant, since half of him is free, and a free Jew may not marry a Canaanite maidservant. He is also not able to marry a free woman, since half of him is a slave, and a Jewish woman may not marry a Canaanite slave. And if you say he should be idle and not marry, but is it not true that the world was created only for procreation, as it is stated: “He did not create it to be a waste; He formed it to be inhabited” (Isaiah 45:18)?

The reason the Gemoro invokes the Possuk of “He did not create it to be a waste; He formed it to be inhabited” and not "You shall be fruitdul and multiply" is because a servant (and by way of extrapolation a woman too) is not obligated by way of that commandment but is by way of the former.

You may even sell a Sefer Torah to marry off a woman even though she is not commanded in procreating because she is commanded in "Settling the world".

§ It was stated that amora’im disagreed over the following issue: If a man had children when he was a gentile and he subsequently converted, Rabbi Yoḥanan said: He has already fulfilled the mitzva to be fruitful and multiply.... Rabbi Yoḥanan said he has fulfilled the mitzva to be fruitful and multiply, as he already had children.

It appears from this Gemoro that gentiles too are commanded in procreating.

... Even non-jews are commanded to have children as the Possuk commanding procreation addresses Noach (a gentile).

A non-jewish servant is not commanded in procreating but is required to fulfill the command of settling the land in a functional state.