4.
The Discourse on Mindfulness
410.
"Monks, a monk should dwell mindful.
This is our instruction to you.
And how, monks, is a monk mindful?
Here, monks, a monk dwells observing the body in the body, ardent, fully aware, mindful, having removed covetousness and displeasure regarding the world;
in feelings... etc.
In mind... etc.
He dwells observing mental phenomena in mental phenomena, ardent, fully aware, mindful, having removed covetousness and displeasure regarding the world.
Thus, monks, a monk is mindful.
Monks, a monk should dwell mindful.
This is our instruction to you."
The fourth.