'Circumcision' in the Bible

And He gave to him a covenant of circumcision, and so he begat Isaac, and did circumcise him on the eighth day, and Isaac begat Jacob, and Jacob -- the twelve patriarchs;

and those of the circumcision believing were astonished -- as many as came with Peter -- because also upon the nations the gift of the Holy Spirit hath been poured out,

and when Peter came up to Jerusalem, those of the circumcision were contending with him,