Majjhima Nikaya 2:15
SUJATOKathañca, bhikkhave, bhikkhu kāye kāyānupassī viharati?
And how does a mendicant meditate observing an aspect of the body?
Kathañca, bhikkhave, bhikkhu kāye kāyānupassī viharati?
And how does a mendicant meditate observing an aspect of the body?