Genesis 21:1-7

1And Yhwh visited Sarah as he had said, And Yhwh did unto Sarah as he had spoken. 2For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him. 3And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac. 4And Abraham circumcised his son Isaac being eight days old, as God had commanded him. 5And Abraham was an hundred years old, when his son Isaac was born unto him.

6And Sarah said, God hath made me to laugh, so that all that hear will laugh with me. 7And 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.