Genesis 17:15-21

Then God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. I will bless her, and indeed I will give you a son by her. Then I will bless her, and she shall be a mother of nations; kings of peoples will come from her.” Then Abraham fell on his face and laughed, and said in his heart, “Will a child be born to a man one hundred years old? And will Sarah, who is ninety years old, bear a child?” And Abraham said to God, “Oh that Ishmael might live before You!” But God said, “No, but Sarah your wife will bear you a son, and you shall call his name Isaac; and I will establish My covenant with him for an everlasting covenant for his descendants after him. As for Ishmael, I have heard you; behold, I will bless him, and will make him fruitful and will multiply him exceedingly. He shall become the father of twelve princes, and I will make him a great nation. But My covenant I will establish with Isaac, whom Sarah will bear to you at this season next year.”