13 Circumcise every baby boy whether he is born in your family or bought as a slave. Your bodies will be marked to show that you are part of my agreement that lasts forever.
14 Any male who is not circumcised will be cut off from his people, because he has broken my agreement.”
15 God said to Abraham, “I will change the name of Sarai, your wife, to Sarah.
16 I will bless her and give her a son, and you will be the father. She will be the mother of many nations. Kings of nations will come from her.”
17 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?”
18 Then Abraham said to God, “Please let Ishmael be the son you promised.”
19 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.