Genesis 17:17-24

17Then Abraham fell on his face and laughed, and said in his heart, “Shall a child be born to a man who is a hundred years old? And shall Sarah, who is ninety years old, bear a child?”

18And Abraham said to God, “Oh, that Ishmael [my firstborn] might live before You!”

19But God said, “No, Sarah your wife shall bear you a son indeed, and you shall name him Isaac (laughter); and I will establish My covenant with him for an everlasting covenant and with his descendants after him.

20As for Ishmael, I have heard and listened to you; behold, I will bless him, and will make him fruitful and will greatly multiply him [through his descendants]. He will be the father of twelve princes (chieftains, sheiks), and I will make him a great nation.

21But My covenant [My promise, My solemn pledge], I will establish with Isaac, whom Sarah will bear to you at this time next year.”

22And God finished speaking with him and went up from Abraham.

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

24So Abraham was ninety-nine years old when he was circumcised.