Genesis 17:19-22
17:19 God said, “No, Sarah your wife is going to bear you a son, and you will name him Isaac. I will confirm my covenant with him as a perpetual covenant for his descendants after him.
17:20 As for Ishmael, I have heard you. I will indeed bless him, make him fruitful, and give him a multitude of descendants. He will become the father of twelve princes; I will make him into a great nation.
17:21 But I will establish my covenant with Isaac, whom Sarah will bear to you at this set time next year.”
17:22 When he finished speaking with Abraham, God went up from him.