Majjhima Nikaya 2:113
SUJATOKathañca, bhikkhave, bhikkhu dhammesu dhammānupassī viharati?
And how does a mendicant meditate observing an aspect of principles?
Kathañca, bhikkhave, bhikkhu dhammesu dhammānupassī viharati?
And how does a mendicant meditate observing an aspect of principles?