Chapter XVIII · Śloka 41
ब्राह्मणक्षत्रियविशां शूद्राणां च परन्तप |
कर्माणि प्रविभक्तानि स्वभावप्रभवैर्गुणैः ||
कर्माणि प्रविभक्तानि स्वभावप्रभवैर्गुणैः ||
brāhmaṇa-kṣatriya-viśāṃ śūdrāṇāṃ ca parantapa |
karmāṇi pravibhaktāni svabhāva-prabhavair guṇaiḥ ||
karmāṇi pravibhaktāni svabhāva-prabhavair guṇaiḥ ||
The duties of brāhmaṇas, kṣatriyas, vaiśyas, and śūdras, O scorcher of foes, are distributed according to the qualities born from their own natures.
The four-fold order is grounded not in birth alone but in svabhāva — one's own inherent nature as shaped by the gunas. This verse opens the famous passage on varṇadharma by establishing its basis: what one is equipped to do by nature, that is one's proper sphere of duty.