Genesis 21:4 KJV
And Abraham circumcised his son Isaac being eight days old, as God had commanded him.
Genesis 21:4, King James Version
In context
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.