Genesis 21:2-5

KJV(i) 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.