Gregory the Great — as excerpted in the Catena Aurea on Luke 19:45-48

“(ut sup.) And these make the house of God a den of thieves, because when corrupt men hold religious offices, they slay with the sword of their wickedness their neighbours, whom they ought to raise to life by the intercession of their prayers. The temple also is the soul of the faithful, which if it put forth corrupt thoughts to the injury of a neighbour, then is it become as it were a lurking place of thieves. But when the soul of the faithful is wisely instructed to shun evil, truth teaches daily in the temple.”