Saṃyutta Nikāya 47
Connected Discourses on the Establishments of Mindfulness
46. The Restraint of the Patimokkha
Then a certain bhikkhu approached the Blessed One, paid homage to him, sat down to one side, and said to him: “Venerable sir, it would be good if the Blessed One would teach me the Dhamma in brief, so that, having heard the Dhamma from the Blessed One, I might dwell alone, withdrawn, diligent, ardent, and resolute.”
“In that case, bhikkhu, purify the very beginning of wholesome states. And what is the beginning of wholesome states? Here, bhikkhu, dwell restrained by the restraint of the Patimokkha, accomplished in good conduct and proper resort, seeing danger in the slightest faults. Having undertaken the training rules, train in them. When, bhikkhu, you dwell restrained by the restraint of the Patimokkha … seeing danger in the slightest faults, then, based upon virtue, established upon virtue, you should develop the four establishments of mindfulness.
“What four? Here, bhikkhu, a bhikkhu dwells contemplating the body in the body … feelings in feelings … mind in mind … phenomena in phenomena, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world.
“When, bhikkhu, based upon virtue, established upon virtue, you develop these four establishments of mindfulness in such a way, then, whether night or day comes, you may expect only growth in wholesome states, not decline.”