Genesis 17:19-27

Then God said, “Yes, but your wife Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him. And as for Ishmael, I have heard you: I will surely bless him; I will make him fruitful and will greatly increase his numbers. He will be the father of twelve rulers, and I will make him into a great nation. But my covenant I will establish with Isaac, whom Sarah will bear to you by this time next year.” When he had finished speaking with Abraham, God went up from him. On that very day Abraham took his son Ishmael and all those born in his household or bought with his money, every male in his household, and circumcised them, as God told him. Abraham was ninety-nine years old when he was circumcised, and his son Ishmael was thirteen; Abraham and his son Ishmael were both circumcised on that very day. And every male in Abraham’s household, including those born in his household or bought from a foreigner, was circumcised with him.