משנה אויף בראשית 1:22

A man shall not abstain from procreation unless he already has children. Beth Shammai says: two males, And Beth Hillel says: male and a female, for it says, “Male and female created he them” (Genesis 5:2). If a man married a woman and lived with her for ten years and she bore no child, he may not abstain [any longer from the duty of propagation]. If he divorced her she is permitted to marry another, and the second husband may also live with her for ten years. If she miscarried [the period of ten years] is counted from the time of her miscarriage. A man is commanded concerning the duty of propagation but not a woman. Rabbi Yohanan ben Beroka says: Concerning both of them it is said, “And God blessed them; and said to them… “Be fruitful and multiply” (Genesis 1:28).