Genesis 21:4 in the World English Bible
Abraham circumcised his son, Isaac, when he was eight days old, as God had commanded him.
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.