15God said to Abraham, “As for Sarai your wife, you shall not call her Sarai anymore, but her name will be Sarah. 16I will bless her and even give you a son by her. Yes, I will bless her, and she will be a mother of nations. Kings of many peoples will come from her.”
17Then Abraham fell on his face and laughed and said in his heart, “Will a child be born to someone who is one hundred years old? Will Sarah, who is ninety years old, give birth?” 18And Abraham said to God, “Oh, let Ishmael live in your presence!”
19But God said, “No, Sarah, your wife, will bear a son for you. You shall name him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him.