ماجهيما نيكايا 2:110
SUJATOEvampi kho, bhikkhave, bhikkhu citte cittānupassī viharati.
That’s how a mendicant meditates by observing an aspect of the mind.
Evampi kho, bhikkhave, bhikkhu citte cittānupassī viharati.
That’s how a mendicant meditates by observing an aspect of the mind.