Genesis 17:13

He that is born in thine house, and he that is bought with
thy money, must needs be circumcised
Or "in circumcising shall be circumcised" ^F12, shall certainly be circumcised; this is repeated to denote the necessity of it, and what care should be taken that this be done, because there was to be no uncircumcised male among them, ( Genesis 17:10 ) ; nor any conversation and communion to be had among them, especially in a religious way.

And my covenant shall be in your flesh for an everlasting covenant;
circumcision was to be seen in their flesh, and no methods were to be taken to draw over the foreskin again, but it was to continue as long as they lived; and so in their posterity, in all succeeding ages, as a sign of the covenant and promise which should remain until the Messiah's coming.