At Thorny Wood (1st)Paṭhamakaṇḍakīsutta

At one time the venerables Anuruddha, Sāriputta, and Mahāmoggallāna were staying near Sāketa in the Thorny Wood.Ekaṁ samayaṁ āyasmā ca anuruddho āyasmā ca sāriputto āyasmā ca mahāmoggallāno sākete viharanti kaṇḍakīvane. Then in the late afternoon, Sāriputta and Mahāmoggallāna came out of retreat, went to Anuruddha, and exchanged greetings with him.Atha kho āyasmā ca sāriputto āyasmā ca mahāmoggallāno sāyanhasamayaṁ paṭisallānā vuṭṭhitā yenāyasmā anuruddho tenupasaṅkamiṁsu; upasaṅkamitvā āyasmatā anuruddhena saddhiṁ sammodiṁsu. When the greetings and polite conversation were over, they sat down to one side. Sāriputta said to Anuruddha:Sammodanīyaṁ kathaṁ sāraṇīyaṁ vītisāretvā ekamantaṁ nisīdiṁsu. Ekamantaṁ nisinno kho āyasmā sāriputto āyasmantaṁ anuruddhaṁ etadavoca:

“Reverend Anuruddha, what things should a trainee mendicant enter and remain in?”“sekhenāvuso anuruddha, bhikkhunā katame dhammā upasampajja vihātabbā”ti?

“Reverend Sāriputta, a trainee mendicant should enter and remain in the four kinds of mindfulness meditation.“Sekhenāvuso sāriputta, bhikkhunā cattāro satipaṭṭhānā upasampajja vihātabbā. 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.Idhāvuso, bhikkhu kāye kāyānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṁ; They meditate observing an aspect of feelings …vedanāsu …pe… mind …citte …pe… principles—keen, aware, and mindful, rid of covetousness and displeasure for the world.dhammesu dhammānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṁ— A trainee mendicant should enter and remain in these four kinds of mindfulness meditation.”sekhenāvuso sāriputta, bhikkhunā ime cattāro satipaṭṭhānā upasampajja vihātabbā”ti.