Genesis 21:3

¹  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.