In Ambapālī’s Mango GroveAmbapālisutta

So I have heard.Evaṁ me sutaṁ— At one time the Buddha was staying near Vesālī in Ambapālī’s Mango Grove.ekaṁ samayaṁ bhagavā vesāliyaṁ viharati ambapālivane. There the Buddha addressed the mendicants,Tatra kho bhagavā bhikkhū āmantesi: “Mendicants!”“bhikkhavo”ti.

“Venerable sir,” they replied.“Bhadante”ti te bhikkhū bhagavato paccassosuṁ. The Buddha said this:Bhagavā etadavoca:

“Mendicants, the four kinds of mindfulness meditation are the path to convergence. They are in order to purify sentient beings, to get past sorrow and crying, to make an end of pain and sadness, to discover the system, and to realize extinguishment.“Ekāyanvāyaṁ, bhikkhave, maggo sattānaṁ visuddhiyā sokaparidevānaṁ samatikkamāya dukkhadomanassānaṁ atthaṅgamāya ñāyassa adhigamāya nibbānassa sacchikiriyāya, yadidaṁ—cattāro satipaṭṭhānā. What four?Katame cattāro?

It’s when a mendicant meditates by observing an aspect of the body—keen, aware, and mindful, rid of covetousness and displeasure for the world.Idha, bhikkhave, bhikkhu kāye kāyānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṁ;

They meditate observing an aspect of feelings—keen, aware, and mindful, rid of covetousness and displeasure for the world.vedanāsu vedanānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṁ;

They meditate observing an aspect of the mind—keen, aware, and mindful, rid of covetousness and displeasure for the world.citte cittānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṁ;

They meditate observing an aspect of principles—keen, aware, and mindful, rid of covetousness and displeasure for the world.dhammesu dhammānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṁ.

The four kinds of mindfulness meditation are the path to convergence. They are in order to purify sentient beings, to get past sorrow and crying, to make an end of pain and sadness, to discover the system, and to realize extinguishment.”Ekāyanvāyaṁ, bhikkhave, maggo sattānaṁ visuddhiyā sokaparidevānaṁ samatikkamāya dukkhadomanassānaṁ atthaṅgamāya ñāyassa adhigamāya nibbānassa sacchikiriyāya, yadidaṁ—cattāro satipaṭṭhānā”ti.

That is what the Buddha said.Idamavoca bhagavā. Satisfied, the mendicants approved what the Buddha said.Attamanā te bhikkhū bhagavato bhāsitaṁ abhinandunti.