四分律刪補隨機羯磨 2.205

2.205

(At that time, various bhikṣus dwelt together and observed the practice of dumb silence. The Buddha rebuked them in various ways, saying: "This is the practice of the white sheep non-Buddhists! From now on, I permit you to mutually examine each other to know whether there is guilt or absence of guilt. Because there are ten benefits, the True Dharma may dwell long; upon concluding the retreat, one should perform pravāraṇā.")