15 And God said to Abraham, “as for Sarai your wife, you shall not call her name Sarai, for Sarah shall be her name.
16 And I will bless her; moreover, I give to you from her a son. And I will bless her, and she shall give rise to nations. Kings of peoples shall come from her.”
17 And Abraham fell upon his face and laughed. And he said in his heart, “Can a child be born to a man a hundred years old, or can Sarah bear a child at ninety?”
18 And Abraham said to God, “Oh that Ishmael might live before you!”
19 And God said, “No, but Sarah your wife shall bear a son for you, and you shall call his name Isaac. And I will establish my covenant with him as an everlasting covenant to his offspring after him.
20 And as for Ishmael, I have heard you. Behold, I will bless him and I will make him fruitful, and I will multiply him exceedingly. He shall father twelve princes, and I will make him a great nation.
21 But my covenant I will establish with Isaac, whom Sarah shall bear to you at this appointed time next year.”