Genesis 17:15-19

God said to Abraham, “As for your wife Sarai, do not call her Sarai, for Sarah will be her name. I will bless her; indeed, I will give you a son by her. I will bless her, and she will produce nations; kings of peoples will come from her.” Abraham fell facedown. Then he laughed and said to himself, “Can a child be born to a hundred-year-old man? Can Sarah, a ninety-year-old woman, give birth?” So Abraham said to God, “If only Ishmael were acceptable to you!” But God said, “No. Your wife Sarah will bear you a son, and you will name him Isaac. I will confirm my covenant with him as a permanent covenant for his future offspring.