John Calvin Commentary 1 Thessalonians 2:5

"For neither at any time were we found using words of flattery, as ye know, nor a cloak of covetousness, God is witness;" — 1 Thessalonians 2:5 (ASV)

For neither have we ever. It is not without good reason that he repeats this so frequently, so that the Thessalonians knew that what he states is true. For there is no surer testimony than the experience of those with whom we speak. This was of the greatest importance to them, because Paul relates the integrity with which he had conducted himself, with no other intention than that his doctrine might receive greater respect, for the building up of their faith.

This is, however, a confirmation of the previous statement, for he who desires to please men must necessarily stoop shamefully to flattery, while he who is intent on duty with an earnest and upright disposition will keep far from all appearance of flattery.

When he adds, nor for an occasion of covetousness, he means that, in teaching among them, he had not been seeking any personal gain. Πρόφασις is used by the Greeks to mean both occasion and pretext, but the former meaning suits the passage better, so as to be, as it were, a trap.

“I have not abused the gospel so as to make it an occasion for seeking gain.” However, because human malice has so many hidden ways that avarice and ambition frequently lie concealed, he for this reason calls God to witness. He mentions two vices here from which he declares himself to be free, and, in doing so, teaches that Christ’s servants should keep away from them.

Thus, if we are to distinguish the genuine servants of Christ from those who are false and counterfeit, they must be tested by this rule, and everyone who would serve Christ rightly must also conform their aims and actions to the same rule. For where avarice and ambition reign, countless corruptions follow, and the whole person degenerates into futility, for these are the two sources from which the corruption of the entire ministry originates.