16 I will bless her, and you will have a son by her. She will become the mother of nations, and some of her descendants will even be kings.
17 Abraham bowed with his face to the ground and thought, “I am almost a hundred years old. How can I become a father? And Sarah is ninety. How can she have a child?” So he started laughing.
18 Then he asked God, “Why not let Ishmael inherit what you have promised me?”
19 But God answered:No! You and Sarah will have a son. His name will be Isaac, and I will make an everlasting promise to him and his descendants.
20 I have heard what you asked me to do for Ishmael, and so I will also bless him with many descendants. He will be the father of twelve princes, and I will make his family a great nation.
21 But your son Isaac will be born about this time next year, and the promise I am making to you and your family will be for him and his descendants for ever.
22 God finished speaking to Abraham and then left.