Genesis 17:23-27

So Abraham took Ishmael his son, all who were born in his house and all who were bought with his money, every male among the men of Abraham’s house, and circumcised the flesh of their foreskins that very same day, as God had said to him. Abraham was ninety-nine years old 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. That very same day Abraham was circumcised, and his son Ishmael; and all the men of his house, born in the house or bought with money from a foreigner, were circumcised with him.