Mahasatipatthana Sutta
iii. Sampajanna Pabba (Section on Clear Understanding)

And again, bhikkhus, a bhikkhu, while going forward or while going back does so with clear understanding;note39 while looking straight ahead or while looking elsewhere he does so with clear understanding; while bending or stretching his limbs he does so with clear understanding; while carrying the alms bowl and while wearing the robes he does so with clear understanding; while eating, drinking, chewing, and savouring he does so with clear understanding; while urinating or defecating he does so with clear understanding; while walking, standing, sitting, falling asleep, waking, speaking or when remaining silent, he does so with clear understanding.

Thus he dwells perceiving again and again the body, as just the body in himself… Thus, bhikkhus, this is also a way in which a bhikkhu dwells perceiving again and again the body as just the body.