Genesis 17:15-27 Revised Standard Version (RSV)
15 And God said to Abraham, “As for Sar′ai your wife, you shall not call her name Sar′ai, but Sarah shall be her name. 16 I will bless her, and moreover I will give you a son by her; I will bless her, and she shall be a mother of nations; kings of peoples shall come from her.” 17 Then Abraham fell on his face and laughed, and said to himself, “Shall a child be born to a man who is a hundred years old? Shall Sarah, who is ninety years old, bear a child?” 18 And Abraham said to God, “O that Ish′mael might live in thy sight!” 19 God said, “No, but Sarah your wife shall bear you a son, and you shall call his name Isaac.[a] I will establish my covenant with him as an everlasing covenant for his descendants after him. 20 As for Ish′mael, I have heard you; behold, I will bless him and make him fruitful and multiply him exceedingly; he shall be the father of twelve princes, and I will make him a great nation. 21 But I will establish my covenant with Isaac, whom Sarah shall bear to you at this season next year.”
22 When he had finished talking with him, God went up from Abraham. 23 Then Abraham took Ish′mael his son and all the slaves born in his house or bought with his money, every male among the men of Abraham’s house, and he circumcised the flesh of their foreskins that very day, as God had said to him. 24 Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. 25 And Ish′mael his son was thirteen years old when he was circumcised in the flesh of his foreskin. 26 That very day Abraham and his son Ish′mael were circumcised; 27 and all the men of his house, those born in the house and those bought with money from a foreigner, were circumcised with him.