21 The Lord was gracious to Sarah, just as he had said he would be. He did for Sarah what he had promised to do. 2Sarah became pregnant. She had a son by Abraham when he was old. He was born at the exact time God had promised him.
3Abraham gave the name Isaac to the son Sarah had by him. 4When his son Isaac was eight days old, Abraham circumcised him. He did it exactly as God had commanded him. 5Abraham was 100 years old when his son Isaac was born to him.