Genesis 17:25 in the King James Version
And Ishmael his son was thirteen years old, when he was circumcised in the flesh of his foreskin.
Context
24 Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin.
25 Ishmael, his son, was thirteen years old when he was circumcised in the flesh of his foreskin.
26 In the same day both Abraham and Ishmael, his son, were circumcised.