The Blessed One said:
"This way, the four foundations of awareness, has the one purpose of
purifying beings, overcoming sorrow and lamentation, destroying pain
and grief, attaining the right path, and realising nibbana."
"What are the four?"
"Here a bhikkhu, surrendering desire and grief regarding the world,
lives contemplating body as body, ardent (atapi), clearly
comprehending (sampajano) and aware (satima)."
"Surrendering desire and grief regarding the world, he lives
contemplating sensations as sensations, ardent, clearly
comprehending and aware."
"Surrendering desire and grief regarding the world, he lives
contemplating mind as mind, ardent, clearly comprehending and
aware."
"Surrendering desire and grief regarding the world, he lives
contemplating dhammas as dhammas, ardent, clearly comprehending
and aware."