Galatians 2:2-5

I went up because of a revelation and set before them (though privately before those who seemed influential) the gospel that I proclaim among the Gentiles, in order to make sure I was not running or had not run in vain. But even Titus, who was with me, was not forced to be circumcised, though he was a Greek. Yet because of false brothers secretly brought in—who slipped in to spy out our freedom that we have in Christ Jesus, so that they might bring us into slavery— to them we did not yield in submission even for a moment, so that the truth of the gospel might be preserved for you.