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 give thee a son also of her: yea, I will bless her, and she shall be a mother of nations; kings of people 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 an hundred years old? and shall Sarah, that is ninety years old, bear?18And Abraham said unto God, O that Ishmael might live before thee!19And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with 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, which Sarah shall bear unto thee at this set time in the next year.

9And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent.10And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him.11Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women.12Therefore Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also?13And the LORD said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, which am old?14Is any thing too hard for the LORD? At the time appointed I will return unto thee, according to the time of life, and Sarah shall have a son.15Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh.