Musar do Rodzaju 1:22

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". We have devoted considerable space to discussing that commandment in connection with the discussion in the Talmud Yevamot that failure to comply with this commandment is very serious. This commandment is obligatory for males only. Rabbi Yochanan ben Broka notes that in both instances this commandment is introduced in the Torah as a blessing, i.e. "G–d blessed them and said to them…" From this he concludes that the commandment applies equally to both men and women. The author of the Mishnah in Yevamot 65 bases his statement that only males are obligated to procreate on the fact that only males are in the habit of "conquering," and that the Torah connects the commandment with the directive to "conquer or subdue" the earth (Genesis 1,28). At any rate, both these rabbis understand the words פרו ורבו, "be fruitful and multiply," as a command. Bar Kappara in Ketuvot 5 says that the reason a widow should be married on Thursday evening is that when cohabitation takes place this will be on Friday, the day that G–d blessed mankind with the blessing to be fruitful.

Although one could conclude that he views the verse as being only a blessing, just as in Genesis 1,22 when G–d blessed the creatures of the waters, using the same expression, it would be a grave error to accuse Bar Kappara of disagreeing with the views of the scholars in Yevamot. All the sages are agreed that, unlike the blessing for the fish, the verses in question are both a blessing and a commandment. In the case of the blessing for the fish this is not followed by another directive such as when G–d addressed man. There it says ויאמר להם…, "G–d said to them. .." The blessing aspect must be understood as being a result of fulfilling the commandment to procreate. The nature of the blessing is that procreation will be successful, i.e. man will multiply, be healthy, etc.

G–d called upon Rahav, the guardian angel of Ishmael, asking whether he wanted to accept the Torah. Rahav also wanted to know what is written in the Torah; G–d told him that the Torah prohibits adultery. This proved unacceptable to the representative of Ishmael who considered his whole kingdom on earth as based on the blessing of water, i.e. the blessing given to the fish in Genesis 1,22 to multiply indiscriminately without regard to exclusive sexual pairings. When the angel told Hagar that she would give birth to Ishmael (Genesis 16,11), he told her that Ishmael would be פרא אדם, "an unbridled human being." [the word פרא here seems related to פרו in the way the Zohar uses it. Ed.] Rahav began to plead with G–d: "Abraham had two sons.; You have the choice of giving the Torah to one of Isaac's two sons. The Torah is far more suitable for either of them than for Ishmael." G–d responded that this would not be fair because Ishmael was Abraham's first-born." The guardian angel of Ishmael then offered to waive his claim to the birthright of Ishmael in favour of Isaac. He offered to also cede to Isaac and his descendants the "light" Ishmael had inherited by dint of being Abraham's first-born son. G–d accepted this offer, and this is why the Torah says: הופיע מהר פארן.