Chapter 18 · verse 26 · gita.yoga.org

Bhagavad Gita 18.26

मुक्तसङ्गोऽनहंवादी धृत्युत्साहसमन्वितः।सिद्ध्यसिद्ध्योर्निर्विकारः कर्ता सात्त्विक उच्यते

An agent who is free from attachment, non-egoistic, endowed with firmness and enthusiasm, and unaffected by success or failure, is considered to be of a Sattvic (pure) nature.