Genesis
Chapters 21:1-4
Amplified Bible
1THE Lord visited Sarah as He had said, and the Lord did for her as He had promised.
2For Sarah became pregnant and bore Abraham a son in his old age, at the set time God had told him.
3Abraham named his son whom Sarah bore to him Isaac [laughter].
4And Abraham circumcised his son Isaac when he was eight days old, as God had commanded him.