Genesis 17:12-13

12And every male among you who is 1eight days old shall be circumcised throughout your generations, a servant who is born in the house or who is bought with money from any foreigner, who is not of your 2descendants.

13A servant who is born in your house or 3who is bought with your money shall surely be circumcised; thus shall My covenant be in your flesh for an everlasting covenant.