Genesis 17:9-11 ‘Then God said to Abraham, “As for you, keep my covenant, you and your descendants after you for the generations to come by circumcising every male among you. You are to undergo circumcision, and it will be the sign of the covenant between me and you...” ‘God also said to Abraham, “As for Sarai your wife, you are no longer to call her Sarai; her name will be Sarah. I will bless her and will surely give you a son by her. I will bless her so that she will be the mother of nations; kings of peoples will come from her.’ Genesis 17:15-16 Abraham fell facedown; he laughed and said to himself, “Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?” He also said, “If only Ishmael might live under your blessing!”   “Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him. As for Ishmael, I have heard you: I will surely bless him; I will make him fruitful and he will greatly increase his numbers... But my covenant I will establish with Isaac, whom Sarah will bear to you by this time next year.” Genesis 17-27