Genesis 17:23-25

New Revised Standard Version Catholic Edition

²³ Then Abraham took his son Ishmael and all the slaves born in his house or bought with his money, every male among the men of Abraham’s house, and he circumcised the flesh of their foreskins that very day, as God had said to him. ²⁴ Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. ²⁵ And his son Ishmael was thirteen years old when he was circumcised in the flesh of his foreskin.