Genesis 17:6-11

I will make you exceedingly fruitful; and I will make nations of you, and kings shall come from you. And I will establish My covenant between Me and you and your descendants after you in their generations, for an everlasting covenant, to be God to you and your descendants after you. Also I give to you and your descendants after you the land in which you are a stranger, all the land of Canaan, as an everlasting possession; and I will be their God.” And God said to Abraham: “As for you, you shall keep My covenant, you and your descendants after you throughout their generations. This is My covenant which you shall keep, between Me and you and your descendants after you: Every male child among you shall be circumcised; and you shall be circumcised in the flesh of your foreskins, and it shall be a sign of the covenant between Me and you.