Albert Barnes Commentary Acts 16:18

"And this she did for many days. But Paul, being sore troubled, turned and said to the spirit, I charge thee in the name of Jesus Christ to come out of her. And it came out that very hour." — Acts 16:18 (ASV)

But Paul, being grieved—that is, being harassed, troubled, or offended. Paul was grieved, probably, for the following reasons:

1. Because her presence was troublesome to him;
2. Because it might be said that he was in alliance with her, and that his claims were just like hers;
3. Because what she did was for the sake of gain and was a base imposition;
4. Because her state was one of bondage and delusion, and it was proper to free her from this demonic possession; and
5. Because the system under which she was acting was part of a vast scheme of delusion and imposture, which had spread over a large portion of the pagan world and was then holding it in bondage. Throughout the Roman Empire, the inspiration of the priestesses of Apollo was believed in, and temples were everywhere erected to perpetuate and celebrate this delusion.

Christianity had to set itself against this extensive system of imposture and fraud; and this was a favorable opportunity to expose the delusion and to show the power of the Christian religion over all the arts and powers of imposture. The mere fact that in a very few instances—of which this was one—they spoke the truth, did not make it improper for Paul to intervene.

That fact would only tend to perpetuate the delusion and make his intervention more proper and necessary. The expulsion of the evil spirit would also afford a striking proof of the fact that the apostles were really from God—a far better proof than her noisy and troublesome proclamation of it would provide.

In the name of Jesus Christ. Or, by the authority of Jesus Christ. (See Barnes, Acts 3:6).