Commentary for Avodah Zarah 53:10

ולמאן דאמר המול ימול איכא והתנן קונם שאני נהנה מן הערלים מותר בערלי ישראל ואסור במולי עובדי כוכבים אלמא אף על גב דמהילי כמאן דלא מהילי דמו

But according to the one who says, “He who is circumcised shall circumcise” is he really allowed, have we not learned, [He who says], “I vow not to derive benefit anything belonging to uncircumcised persons,” may derive benefit from uncircumcised Israelites, but may not derive benefit from circumcised non-Jew. Thus, even though they are circumcised it is as if they are uncircumcised.

Daf Shevui to Avodah Zarah