The Tipiṭaka in Three Languages

Suññatavāra

Abhidhammapiṭaka · Dhammasaṅgaṇī · Vol. 34 · Section 410

[410] What on that occasion is the faculty of equanimity (upekkhindriya)? That which on that occasion is neither mental ease nor mental unease; the neither-painful-nor-pleasant felt experience born of mind-contact (cetosamphassa); the neither-painful-nor-pleasant feeling (vedanā) born of mind-contact — this on that occasion is the faculty of equanimity.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 5 other places