From: Luke 4:31-37
Jesus Preaches in Capernaum
 And He (Jesus) went down to Capernaum, a city of Galilee. And He was teaching them on the Sabbath; and they were astonished at His teaching, for His word was with authority.
The Cure of the Demoniac
 And in the synagogue there was a man who had the spirit of an unclean demon; and he cried out with a loud voice,  "Ah! What have You to do with us, Jesus of Nazareth? Have You come to destroy us? I know who You are, the Holy One of God."  But Jesus rebuked him, saying, "Be silent, and come out of him!" And when the demon had thrown him down in the midst, he came out of him, having done him no harm. And they were all amazed and said to one another, "What is this word? For with authority and power He commands the unclean spirits, and they come out."  And reports of Him went out into every place in the surrounding region.
33-37. Jesus now demonstrates by His actions that authority which was evident in His words.
34. The demon tells the truth here when he calls Jesus "the Holy One of God", but Jesus does not accept this testimony from the "father of lies" (John 8:44). This shows that the devil usually says something partially true in order to disguise untruth; by sowing confusion in this way, he can more readily deceive people. By silencing and expelling the demon, Jesus teaches us to be prudent and not let ourselves by deceived by half-truths.
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.