Genesis 21:4-8

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

And Abraham was an hundred years old, when his son Isaac was born unto 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.

And the child grew, and was weaned: and Abraham made a great feast the same day that Isaac was weaned.