Majjhima Nikaya (Coleção dos Discursos Médios) 2:10
SUJATOvedanāsu vedanānupassī 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.