Gn 17:15-22

15God further said to Abraham: As for Sarai your wife, do not call her Sarai; her name will be Sarah.^* 16I will bless her, and I will give you a son by her. Her also will I bless; she will give rise to nations, and rulers of peoples will issue from her.^j 17Abraham fell face down and laughed^* as he said to himself, “Can a child be born to a man who is a hundred years old? Can Sarah give birth at ninety?”^k 18So Abraham said to God, “If only Ishmael could live in your favor!” 19God replied: Even so, your wife Sarah is to bear you a son, and you shall call him Isaac. It is with him that I will maintain my covenant as an everlasting covenant and with his descendants after him.^l 20Now as for Ishmael, I will heed you: I hereby bless him. I will make him fertile and will multiply him exceedingly. He will become the father of twelve chieftains, and I will make of him a great nation.^m 21But my covenant I will maintain with Isaac, whom Sarah shall bear to you by this time next year.ⁿ 22When he had finished speaking with Abraham, God departed from him.