Albert Barnes Commentary Acts 19:17

"And this became known to all, both Jews and Greeks, that dwelt at Ephesus; and fear fell upon them all, and the name of the Lord Jesus was magnified." — Acts 19:17 (ASV)

The name of the Lord Jesus was magnified. It acquired increasing honour. This event showed that the miracles Paul performed in the name of the Lord Jesus were real, and were worked to confirm the truth of the doctrine he taught. Impostors could not work such miracles; and those who pretended to be able to do so only exposed themselves to the rage of the evil spirits. It was thus shown that there was a real, vital difference between Paul and these impostors; and their failure only served to extend his reputation and the power of the gospel.