Genesis 17:15-19

Then God said to Abraham, “As for your wife Sarai, you shall not call her by the name Sarai, but Sarah shall be her name.

I will bless her, and indeed I will give you a son by her. Then I will bless her, and she shall be a mother of nations; kings of peoples will come from her.”

Then Abraham fell on his face and laughed, and said in his heart, “Will a child be born to a man a hundred years old? And will Sarah, who is ninety years old, give birth to a child?”

And Abraham said to God, “Oh that Ishmael might live before You!”

But God said, “No, but your wife Sarah will bear you a son, and you shall name him Isaac; and I will establish My covenant with him as an everlasting covenant for his descendants after him.