Genesis 21:1-6
The Birth of Isaac
21:1 The Lord visited Sarah just as he had said he would and did for Sarah what he had promised.
21:2 So Sarah became pregnant and bore Abraham a son in his old age at the appointed time that God had told him.
21:3 Abraham named his son – whom Sarah bore to him – Isaac.
21:4 When his son Isaac was eight days old, Abraham circumcised him just as God had commanded him to do.
21:5 (Now Abraham was a hundred years old when his son Isaac was born to him.)
21:6 Sarah said, “God has made me laugh. Everyone who hears about this will laugh with me.”