1.
The Discourse on Concentration
249.
"There are these three feelings, monks.
Which three?
Pleasant feeling, unpleasant feeling, neither-unpleasant-nor-pleasant feeling -
these, monks, are the three feelings."
"Concentrated, fully aware, mindful, a disciple of the Buddha;
He understands feelings, and the origination of feelings.
"Where these cease, and the path leading to their elimination;
Through the elimination of feelings, a monk is without hunger, attained final Nibbāna." The first.