Genesis 21:5

And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac.

And Abraham circumcised his son Isaac being eight days old, as God had commanded him.

And Sarah said, God hath made me to laugh, so that all that hear will laugh with me.

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.