Genesis 17:23-26

23And Abraham took Ishmael his son, and all that were born in his house, and all that were bought with his money, every male among the men of Abraham’s house; and circumcised the flesh of their foreskin in the selfsame day, as God had said unto him. 24And Abraham was ninety years old and nine, when he was circumcised in the flesh of his foreskin. 25And Ishmael his son was thirteen years old, when he was circumcised in the flesh of his foreskin. 26In the selfsame day was Abraham circumcised, and Ishmael his son.