Genesis 17:9-11

Young's Literal Translation

⁹ And God saith unto Abraham, `And thou dost keep My covenant, thou and thy seed after thee, to their generations;

¹⁰ this [is] My covenant which ye keep between Me and you, and thy seed after thee: Every male of you [is] to be circumcised;

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