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 [As to his outward conduct (that it was without flattery) he calls the Thessalonians to witness, and as to his inward desires (that they were without covetousness) he calls God to witness. Self-seeking and flattery were the besetting sins of false teachers (Romans 16:18). Paul had spoken plainly of the sins of his hearers, and had demanded immediate and thorough repentance];