Acts 19:13-16 NIV
Some Jews who went around driving out evil spirits tried to invoke the name of the Lord Jesus over those who were demon-possessed. They would say, “In the name of the Jesus whom Paul preaches, I command you to come out.” Seven sons of Sceva, a Jewish chief priest, were doing this. One day the evil spirit answered them, “Jesus I know, and Paul I know about, but who are you?” Then the man who had the evil spirit jumped on them and overpowered them all. He gave them such a beating that they ran out of the house naked and bleeding.
NIV: New International Version