Gen 21:1-8

The LORD took note of Sarah as he had said he would; the LORD did for her as he had promised. Sarah became pregnant and bore Abraham a son in his old age, at the set time that God had stated. Abraham gave the name Isaac to this son of his whom Sarah bore him. When his son Isaac was eight days old, Abraham circumcised him, as God had commanded. Abraham was a hundred years old when his son Isaac was born to him. Sarah then said, “God has given me cause to laugh, and all who hear of it will laugh with me. Who would ever have told Abraham,” she added, “that Sarah would nurse children! Yet I have borne him a son in his old age.” The child grew and was weaned, and Abraham held a great banquet on the day of the child’s weaning.