Genesis 17:20

16I will bless her, and moreover I will give you a son by her. Yes, I will bless her, and she will be a mother of nations. Kings of peoples will come from her.”

17Then Abraham fell on his face, and laughed, and said in his heart, “Will a child be born to him who is one hundred years old? Will Sarah, who is ninety years old, give birth?”

18Abraham said to God, “Oh that Ishmael might live before you!”

19God said, “No, but Sarah, your wife, will bear you a son. You shall call his name Isaac. I will establish my covenant with him for an everlasting covenant for his offspring after him.

20As for Ishmael, I have heard you. Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly. He will become the father of twelve princes, and I will make him a great nation.

21But I will establish my covenant with Isaac, whom Sarah will bear to you at this set time next year.”

22When he finished talking with him, God went up from Abraham.

23Abraham took Ishmael his son, all who were born in his house, and all who were bought with his money: every male among the men of Abraham’s house, and circumcised the flesh of their foreskin in the same day, as God had said to him.

24Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin.