Genesis 17:10-12

101This is My covenant, which you shall keep, between Me and you and your 2descendants after you: every male among you shall be circumcised.

11And 3you shall be circumcised in the flesh of your foreskin, and it shall be the sign of the covenant between Me and you.

12And every male among you who is 4eight days old shall be circumcised throughout your generations, including a slave who is born in the house or who is bought with money from any foreigner, who is not of your 5descendants.