Digha Nikaya 2:352
SUJATOEkāyano ayaṁ, bhikkhave, maggo sattānaṁ visuddhiyā sokaparidevānaṁ samatikkamāya dukkhadomanassānaṁ atthaṅgamāya ñāyassa adhigamāya nibbānassa sacchikiriyāya yadidaṁ cattāro satipaṭṭhānāti.
‘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.’