Genesis 21:1-8 King James Version (KJV)
21 And the Lord visited Sarah as he had said, and the Lord did unto Sarah as he had spoken.
2 For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.
3 And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac.
4 And Abraham circumcised his son Isaac being eight days old, as God had commanded him.
5 And Abraham was an hundred years old, when his son Isaac was born unto him.
6 And Sarah said, God hath made me to laugh, so that all that hear will laugh with me.
7 And she said, Who would have said unto Abraham, that Sarah should have given children suck? for I have born him a son in his old age.
8 And the child grew, and was weaned: and Abraham made a great feast the same day that Isaac was weaned.