Genesis 17:10

7And I have established My covenant between Me and you, and your seed after you, throughout their generations, for a perpetual covenant, to become God to you, and to your seed after you;

8and I have given to you, and to your seed after you, the land of your sojournings, the whole land of Canaan, for a continuous possession, and I have become their God.”

9And God says to Abraham, “And you keep My covenant, you and your seed after you, throughout their generations;

10this [is] My covenant which you keep between Me and you, and your seed after you: every male of you [is] to be circumcised;

11and you have circumcised the flesh of your foreskin, and it has become a token of a covenant between Me and you.

12And a son of eight days is circumcised by you; every male throughout your generations, born in the house, or bought with money from any son of a stranger, who is not of your seed;

13he is certainly circumcised who [is] born in your house, or bought with your money; and My covenant has become in your flesh a perpetual covenant;