Genesis 17
19 Ref God said, "No, but Sarah, your wife, will bear you a son. You shall call his name Isaac.{Isaac means "he laughs."} I will establish my covenant with him for an everlasting covenant for his seed after him.
20 Ref As for Ishmael, I have heard you. Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly. He will become the father of twelve princes, and I will make him a great nation.
21 Ref But my covenant I establish with Isaac, whom Sarah will bear to you at this set time in the next year."