Ac 16:16 Now it happened, as we went to prayer, that a certain slave girl possessed with a spirit of divination met us, who brought her masters much profit by fortune-telling.
17 This girl followed Paul and us, and cried out, saying, "These men are the servants of the Most High God, who proclaim to us the way of salvation."
18 And this she did for many days. But Paul, greatly annoyed, turned and said to the spirit, "I command you in the name of Jesus Christ to come out of her." And he came out that very hour.
Paul would not accept endorsement from demons even though they spoke the truth about Paul and company. In the end, it would be detrimental to their ministry. People might think that they were in the same company, in league, with each other, undermining their credibility as a result.