Genesis 17
15 Ref And God said unto Abraham, As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be.
16 Ref And 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.
17 Ref Then 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?