Bhagavad Gita 18.26

मुक्तसङ्गोऽनहंवादी धृत्युत्साहसमन्वितः।सिद्ध्यसिद्ध्योर्निर्विकारः कर्ता सात्त्विक उच्यते ॥१८.२६॥

muktasaṅgo’nahaṃvādī dhṛtyutsāhasamanvitaḥsiddhyasiddhyornirvikāraḥ kartā sāttvika ucyate

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.

गीता