Apophthegmata Patrum, as translated by St. Theophan the Recluse.
298. A brother came to an elder and said to him: Abba! Tell me, how to be saved? The elder said to him: if you come to someone, do not start talking before he asks you. The brother, having come to contrition from these words, made a bow to the elder and said: indeed, I read many books, but nowhere did I find such an instruction. And, having received a great benefit, he left.