Saṃyutta Nikāya 47
Connected Discourses on the Establishments of Mindfulness
“And how, bhikkhus, is a bhikkhu mindful? Here, bhikkhus, a bhikkhu dwells contemplating the body in the body, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world. He dwells contemplating feelings in feelings … mind in mind … phenomena in phenomena, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world. It is in this way, bhikkhus, that a bhikkhu is mindful.
“And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here, bhikkhus, a bhikkhu is one who acts with clear comprehension when going forward and returning; when looking ahead and looking aside; when drawing in and extending the limbs; when wearing his robes and carrying his outer robe and bowl; when eating, drinking, chewing his food, and tasting; when defecating and urinating; when walking, standing, sitting, falling asleep, waking up, speaking, and keeping silent. It is in such a way that a bhikkhu exercises clear comprehension.