Genesis 17:19-27

But God said, “No, but Sarah your wife will bear you a son, and you shall call his name Isaac; and I will establish My covenant with him for an everlasting covenant for his descendants after him. As for Ishmael, I have heard you; behold, I will bless him, and will make him fruitful and will multiply him exceedingly. He shall become the father of twelve princes, and I will make him a great nation. But My covenant I will establish with Isaac, whom Sarah will bear to you at this season next year.” When He finished talking with him, God went up from Abraham. Then Abraham took Ishmael his son, and all the servants who were born in his house and all who were bought with his money, every male among the men of Abraham’s household, and circumcised the flesh of their foreskin in the very same day, as God had said to him. Now 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. In the very same day Abraham was circumcised, and Ishmael his son. All the men of his household, who were born in the house or bought with money from a foreigner, were circumcised with him.