Vedanāsutta

sn47.49:1.1 “Mendicants, there are these three feelings.

sn47.49:1.2 What three?

sn47.49:1.3 Pleasant, painful, and neutral feeling.

sn47.49:1.4 These are the three feelings.

sn47.49:1.5 The four kinds of mindfulness meditation should be developed to completely understand these three feelings.