Genesis 17:1-4, 17-19

When Abram was ninety-nine years old, the LORD appeared to him and said, “I am God Almighty. Obey me and do what is right. I will make an agreement between us, and I will make you the ancestor of many people.” Then Abram bowed facedown on the ground. God said to him, “I am making my agreement with you: I will make you the father of many nations.

Abraham bowed facedown on the ground and laughed. He said to himself, “Can a man have a child when he is a hundred years old? Can Sarah give birth to a child when she is ninety?” Then Abraham said to God, “Please let Ishmael be the son you promised.” God said, “No, Sarah your wife will have a son, and you will name him Isaac. I will make my agreement with him to be an agreement that continues forever with all his descendants.