Then God said, “Yes, but your wife Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him.
Then one of them said, “I will surely return to you about this time next year, and Sarah your wife will have a son.” Now Sarah was listening at the entrance to the tent, which was behind him.
Then he gave Abraham the covenant of circumcision. And Abraham became the father of Isaac and circumcised him eight days after his birth. Later Isaac became the father of Jacob, and Jacob became the father of the twelve patriarchs.