Genesis 17:4-15

As for me, behold, my covenant is with thee, and thou shalt be the father of a multitude of nations. Neither shall thy name any more be called Abram, but thy name shall be Abraham; for the father of a multitude of nations have I made thee. And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee. And I will establish my covenant between me and thee and thy seed after thee throughout their generations for an everlasting covenant, to be a God unto thee and to thy seed after thee. And I will give unto thee, and to thy seed after thee, the land of thy sojournings, all the land of Canaan, for an everlasting possession; and I will be their God. And God said unto Abraham, And as for thee, thou shalt keep my covenant, thou, and thy seed after thee throughout their generations. This is my covenant, which ye shall keep, between me and you and thy seed after thee: every male among you shall be circumcised. And ye shall be circumcised in the flesh of your foreskin; and it shall be a token of a covenant betwixt me and you. And he that is eight days old shall be circumcised among you, every male throughout your generations, he that is born in the house, or bought with money of any foreigner that is not of thy seed. He that is born in thy house, and he that is bought with thy money, must needs be circumcised: and my covenant shall be in your flesh for an everlasting covenant. And the uncircumcised male who is not circumcised in the flesh of his foreskin, that soul shall be cut off from his people; he hath broken my covenant. And God said unto Abraham, As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be.