11 And God did special works of power by the hands of Paul: 12 So that bits of linen and clothing from his body were taken to people who were ill, and their diseases went away from them and the evil spirits went out.
13 But some of the Jews who went from place to place driving out evil spirits, took it on themselves to make use of the name of the Lord Jesus over those who had evil spirits, saying, I give you orders, by Jesus, whom Paul is preaching. 14 And there were seven sons of a man named Sceva, a Jew and a chief priest, who did this. 15 And the evil spirit, answering, said to them, I have knowledge of Jesus, and of Paul, but who are you?
Matthew Henry's Commentary on Acts 19:11-15
Commentary on Acts 19:8-12
(Read Acts 19:8-12)
When arguments and persuasions only harden men in unbelief and blasphemy, we must separate ourselves and others from such unholy company. God was pleased to confirm the teaching of these holy men of old, that if their hearers believed them not, they might believe the works.
Commentary on Acts 19:13-20
(Read Acts 19:13-20)
It was common, especially among the Jews, for persons to profess or to try to cast out evil spirits. If we resist the devil by faith in Christ, he will flee from us; but if we think to resist him by the using of Christ's name, or his works, as a spell or charm, Satan will prevail against us. Where there is true sorrow for sin, there will be free confession of sin to God in every prayer and to man whom we have offended, when the case requires it. Surely if the word of God prevailed among us, many lewd, infidel, and wicked books would be burned by their possessors. Will not these Ephesian converts rise up in judgement against professors, who traffic in such works for the sake of gain, or allow themselves to possess them? If we desire to be in earnest in the great work of salvation, every pursuit and enjoyment must be given up which hinders the effect of the gospel upon the mind, or loosens its hold upon the heart.