Tatiyavibhaṅgasutta

Suttapiṭaka · Saṁyuttanikāya · Mahāvaggasaṁyutta · Vol. 19 · Section 945

[945] And what, bhikkhus, is the equanimity faculty (upekkhindriya)? Whatever is felt, bhikkhus, whether bodily or mental, that is neither agreeable nor disagreeable — this, bhikkhus, is called the equanimity faculty.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.