Genesis 17:17-24

17Then Abraham fell on his face and laughed, and said to his heart, “Will a son be born to a 100-year-old man? Or will Sarah—who is 90 years old—give birth?”

18So Abraham said to God, “If only Ishmael might live before you!”

19But God said, “On the contrary, Sarah your wife will bear you a son and you must name him Isaac. So I will confirm My covenant with him as an everlasting covenant for his seed after him.

20As for Ishmael, I have heard you. See, I have blessed him and I will make him fruitful, and I will multiply him very very much. He will father twelve princes and I will make him a great nation.

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

22When He finished speaking with him, God went up from Abraham.

23Then Abraham took Ishmael his son and all of his house-born slaves and all his purchased slaves—every male among the men of Abraham’s house—and he circumcised the flesh of their foreskin on this very same day, just as God had spoken with him.

24Abraham was 99 years old when he was circumcised in the flesh of his foreskin,