Flattery is insincere, manipulative, and deceptive; it clearly has no place on the lips of one who is preaching the gospel of God. By claiming that he did not once—never—use flattery, Paul is reminding the Thessalonians that he was completely open and sincere in the way he spoke to them. He did not praise them insincerely, trying to appeal to their pride, in order to gain their attention or their money.
5 For we never came with words of flattery, as you know, nor with a pretext for greed God is witness.