Genesis 17:19-22

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.