Genesis 17:19-27

God said, “No, but Sarah your wife shall bear you a son, and you shall call his name Isaac. I will establish my covenant with him as an everlasting covenant for his offspring after him. As for Ishmael, I have heard you; behold, I have blessed him and will make him fruitful and multiply him greatly. He shall father twelve princes, and I will make him into a great nation. But I will establish my covenant with Isaac, whom Sarah shall bear to you at this time next year.” When he had finished talking with him, God went up from Abraham. Then Abraham took Ishmael his son and all those 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. Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. And Ishmael his son was thirteen years old when he was circumcised in the flesh of his foreskin. That very day Abraham and his son Ishmael were circumcised. And all the men of his house, those born in the house and those bought with money from a foreigner, were circumcised with him.