Genesis 17:1-4, 17-19

When Abram was ninety-nine years old, the LORD appeared to Abram and said to him, “I am Almighty God; walk before Me and be blameless. And I will make My covenant between Me and you, and will multiply you exceedingly.” Then Abram fell on his face, and God talked with him, saying: “As for Me, behold, My covenant is with you, and you shall be a father of many nations.

Then Abraham fell on his face and laughed, and said in his heart, “Shall a child be born to a man who is one hundred years old? And shall Sarah, who is ninety years old, bear a child?” And Abraham said to God, “Oh, that Ishmael might live before You!” Then God said: “No, Sarah your wife shall bear you a son, and you shall call his name Isaac; I will establish My covenant with him for an everlasting covenant, and with his descendants after him.