Genesis 17:9-13

⁹God said to Abraham, "As for you, you will keep my covenant, you and your seed after you throughout their generations. ¹⁰This is my covenant, which you shall keep, between me and you and your seed after you. Every male among you shall be circumcised. ¹¹You shall be circumcised in the flesh of your foreskin. It will be a token of a covenant between me and you. ¹²He who is eight days old will be circumcised among you, every male throughout your generations, he who is born in the house, or bought with money of any foreigner who is not of your seed. ¹³He who is born in your house, and he who is bought with your money, must be circumcised. My covenant will be in your flesh for an everlasting covenant.