15. God said to Abraham, “You must no longer call your wife Sarai; from now on her name is Sarah.
16. I will bless her, and I will give you a son by her. I will bless her, and she will become the mother of nations, and there will be kings among her descendants.”
17. Abraham bowed down with his face touching the ground, but he began to laugh when he thought, “Can a man have a child when he is a hundred years old? Can Sarah have a child at ninety?”
18. He asked God, “Why not let Ishmael be my heir?”
19. But God said, “No. Your wife Sarah will bear you a son and you will name him Isaac. I will keep my covenant with him and with his descendants for ever. It is an everlasting covenant.
20. I have heard your request about Ishmael, so I will bless him and give him many children and many descendants. He will be the father of twelve princes, and I will make a great nation of his descendants.
21. But I will keep my covenant with your son Isaac, who will be born to Sarah about this time next year.”
22. When God finished speaking to Abraham, he left him.
23. On that same day Abraham obeyed God and circumcised his son Ishmael and all the other males in his household, including the slaves born in his home and those he had bought.