Avassutapariyāya Sutta.– Having just built a new Council Hall at Kapilavatthu, the Sākyā invite the Buddha to make use of it. He teaches them far into the night, then after they have left, he invites Mahā-Moggallāna to speak to the monks.
Mahā-Moggallāna teaches a long discourse on the corrupted and uncorrupted. When a monk dwells without mindfulness, on seeing a sight with the eye, hearing a sound with the ear, etc., his mind is corrupted, and he does not understand the liberation of the mind. However, if a monk dwells with mindfulness, his mind is not corrupted, and he understands the liberation of the mind.
If he is practising properly, a monk cannot be tempted to give up the holy life. (S.iv.183 ﬀ)