'Of the Circumcision' in the Bible

What then is the advantage of the Jew, or what the profit of the circumcision?

And the father of the circumcision, to them who not only are of the circumcision, but also walk in the footsteps of that faith of our father Abraham, which he had in uncircumcision.

Now I say, Christ Jesus was a servant of the circumcision, for the truth of God, to confirm the promises made to the fathers: