Genesis 17:17-24

17Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born to him that is an hundred years old? and shall Sarah, who is ninety years old, bear? 18And Abraham said to God, O that Ishmael might live before thee! 19And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him. 20And as for Ishmael, I have heard thee: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation. 21But my covenant will I establish with Isaac, whom Sarah shall bear to thee at this set time in the next year. 22And he finished talking with him, and God went up from Abraham.

23And Abraham took Ishmael his son, and all that were born in his house, and all that 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. 24And Abraham was ninety and nine years old, when he was circumcised in the flesh of his foreskin.