Genesis 17:25 in the World English Bible
Ishmael, his son, was thirteen years old when he was circumcised in the flesh of his foreskin.
Context
24 And Abraham was ninety years old and nine, when he was circumcised in the flesh of his foreskin.
25 And Ishmael his son was thirteen years old, when he was circumcised in the flesh of his foreskin.
26 In the selfsame day was Abraham circumcised, and Ishmael his son.