Then God said to Abraham, "As for you, you must keep my covenant. You and your children after you for all time to come must keep it.
"Here is my covenant that you and your children after you must keep. Every male among you must be circumcised.
You must be circumcised. That will be the sign of the covenant between me and you.
It must be done for all time to come. "Every male among you who is eight days old must be circumcised. That includes those who are born in your house. It also includes those who are bought with money from a stranger. Even those who are not your own children must be included.
Any male who is born in your house or bought with your money must be circumcised. "My covenant will last forever. Your body will have the mark of my covenant on it.
"Any male who has not been circumcised will be cut off from his people. He has broken my covenant."
God also said to Abraham, "As for Sarai your wife, do not call her Sarai anymore. Her name will be Sarah.
I will give her my blessing. You can be sure that I will give you a son by her. I will bless her so that she will be the mother of nations. Kings of nations will come from her."
Abraham fell with his face to the ground. He laughed and said to himself, "Will a son be born to a man who is 100 years old? Will Sarah have a child at the age of 90?"
Abraham said to God, "I wish Ishmael could receive your blessing!"
Then God said, "I will bless Ishmael. But your wife Sarah will have a son by you. And you will name him Isaac. I will establish my covenant with him. It will be a covenant that lasts forever. It will be for Isaac and for his family after him.