1 Thessalonians 2:5
For neither at any time used we flattering words, as ye know, nor a cloke of covetousness; God [is] witness:
Note 6 at 1Th 2:5: Paul did not use flattering talk. This is the only time the word "flattering" was used in the New Testament. The Greek word from which "flattering" was translated is "KOLAKEIA," and it refers to insincere talk with the end desire of using someone for one's own selfish interest. Vine's Expository Dictionary states that words of flattery are used "not simply as an effort to give pleasure, but with motives of self-interest."
Note 7 at 1Th 2:5: "Covetousness" is the desire to have what belongs to someone else. It is always used in a negative sense in the New Testament. The basic idea is to cover up one's true motive while desiring what belongs to another. Paul stated "God is witness" that this was never his motive in ministering the Gospel to others.