Sarai becomes Sarah

15 Then God said to Abraham, ‘As for Sarai your wife, do not call her name Sarai, but Sarah. 16 I will bless her, and will give you a son from her: I will bless her, and she will become the mother of nations; kings of peoples will descend from her.’

17 Then Abraham fell on his face and laughed, and said to himself. ‘Will a child be born to one who is an hundred years old? Will Sarah who is ninety years old bear children?’ 18 Abraham said to God, ‘If only Ishmael might live with your blessing!’

19 But God said, ‘No. But Sarah your wife is about to bear your a son; call him Isaac. I will establish my covenant with him for an everlasting covenant for his descendants after him. 20 However I have heard you regarding Ishmael: I have blessed him, and will make him fruitful and his descendants exceedingly many. Twelve princes he will father, and I will make him a great nation. 21 But my covenant I will establish with Isaac, whom Sarah will bear to you at this appointed time next year.’ 22 When he had finished talking with him, God left Abraham.