Church Fathers on Luke 11:15

The Lord had promised that the Holy Spirit should be given to those that asked for it; the blessed effects whereof He indeed clearly shows in the following miracle. Hence it follows, And Jesus was casting out a devil, and it was dumb.

Now he is called as commonly meaning one who does not speak. It is also used for one who does not hear, but more properly who neither hears nor speaks. But he who has not heard from his birth necessarily cannot speak. For we speak those things which we are taught to speak by hearing. If however one has lost his hearing from a disease that has come upon him, there is nothing to hinder him from speaking. But He who was brought before the Lord was both dumb in speech, and deaf…

Now He calls the devil deaf or dumb, as being the cause of this calamity, that the Divine word should not be heard. For the devil, by taking away the quickness of human feeling, blunts the hearing of our soul. Christ therefore comes that He might cast out the devil, and that we might hear the word of truth. For He healed one that He might create a universal foretaste of man’s salvation. Hence it follows, And when he: he had cast out the devil, tile dumb spoke.