15And God said unto Abraham, As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be. 16And I will bless her, and moreover I will give thee a son of her: yea, I will bless her, and she shall be a mother of nations; kings of peoples shall be of her. 17Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is a hundred years old? and shall Sarah, that is ninety years old, bear? 18And Abraham said unto God, Oh that Ishmael might live before thee! 19And God said, Nay, but Sarah thy wife shall bear thee a son; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant for his seed after him. 20And as for Ishmael, I have heard thee: behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation. 21But my covenant will I establish with Isaac, whom Sarah shall bear unto thee at this set time in the next year.