Genesis 17:24-28

And Abraham was ninety years old and nine, when he was circumcised in the flesh of his foreskin.

And Ishmael his son was thirteen years old, when he was circumcised in the flesh of his foreskin.

In the selfsame day was Abraham circumcised, and Ishmael his son.

And all the men of his house, born in the house, and bought with money of the stranger, were circumcised with him.