Galatians 2:3-5

But [all went well, for] not even Titus, who was with me, was compelled [as some had anticipated] to be circumcised, despite the fact that he was a Greek. My concern was because of the false brothers [those people masquerading as Christians] who had been secretly smuggled in [to the community of believers]. They had slipped in to spy on the freedom which we have in Christ Jesus, in order to bring us back into bondage [under the Law of Moses]. But we did not yield to them even for a moment, so that the truth of the gospel would continue to remain with you [in its purity].