Compassion - One of the Lakṣaṇas (fundamental characteristics) of Samyaktva (right faith);
when one's psyche is overflowed by the disposition of kindness, there arise (subtle) psychic vibrations as a result of considering other's pain as one's own pain. Such vibrations are Anukampā (compassion).
anugrahabuddhyā " rdrīkṛtacetasaḥ parapīḍāmātmasaṃsthāmiva kurvato ' nukmpanamanukampā.
(TaBhā 6.13 Vṛ)