Mahabharata 6.40.47

श्रेयान्स्वधर्मो विगुणः परधर्मात्स्वनुष्ठितात्स्वभावनियतं कर्म कुर्वन्नाप्नोति किल्बिषम्

śreyānsvadharmo viguṇaḥ paradharmātsvanuṣṭhitātsvabhāvaniyataṃ karma kurvannāpnoti kilbiṣam

Our plain-language meaning of this verse is waiting for scholar review.