15God said to Abraham, "As for Sarai your wife, you shall not call her name Sarai, but her name will be Sarah.
16I will bless her, and moreover I will give you a son by her. Yes, I will bless her, and she will be a mother of nations. Kings of peoples will come from her."
17Then Abraham fell on his face, and laughed, and said in his heart, "Will a child be born to him who is one hundred years old? Will Sarah, who is ninety years old, give birth?"
18Abraham said to God, "Oh that Ishmael might live before you!"
19God said, "No, but Sarah, your wife, will bear you a son. You shall call his name Isaac. I will establish my covenant with him for an everlasting covenant for his seed after him.
20As 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.
21But my covenant I establish with Isaac, whom Sarah will bear to you at this set time in the next year."
