Saṃyutta Nikāya 36
Connected Discourses on Feeling
9. Impermanent
“Bhikkhus, these three feelings are impermanent, conditioned, dependently arisen, subject to destruction, subject to vanishing, subject to fading away, subject to cessation. What three? Pleasant feeling, painful feeling, neither-painful-nor-pleasant feeling. These three feelings are impermanent, conditioned, dependently arisen, subject to destruction, subject to vanishing, subject to fading away, subject to cessation.”