Thus have I heard. On one occasion the Blessed One was dwelling at Vesali in Ambapali’s Grove. There the Blessed One addressed the bhikkhus thus: “Bhikkhus!”
“Venerable sir!” the bhikkhus replied. The Blessed One said this:
“Bhikkhus, this is the one-way path for the purification of beings, for the overcoming of sorrow and lamentation, for the passing away of pain and displeasure, for the achievement of the method, for the realization of Nibbāna, that is, the four establishments of mindfulness. What four?
“Here, bhikkhus, a bhikkhu dwells contemplating the body in the body, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world. He dwells contemplating feelings in feelings, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world. He dwells contemplating mind in mind, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world. He dwells contemplating phenomena in phenomena, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world.
“This, bhikkhus, is the one-way path for the purification of beings, for the overcoming of sorrow and lamentation, for the passing away of pain and displeasure, for the achievement of the method, for the realization of Nibbāna, that is, the four establishments of mindfulness.”
This is what the Blessed One said. Elated, those bhikkhus delighted in the Blessed One’s statement. sn.v.142