Bhagavad Gita 18.26 Chapter 18, Verse 26

मुक्तसङ्गोऽनहंवादी धृत्युत्साहसमन्वितः ।
सिद्ध्यसिद्ध्योर्निर्विकारः कर्ता सात्त्विक उच्यते ॥१८.२६॥

muktasaṅgo'nahaṃvādī dhṛtyutsāhasamanvitaḥ
siddhyasiddhyornirvikāraḥ kartā sāttvika ucyate

Meaning

The doer who is free from attachment, without egoism, full of resolve and enthusiasm, and unchanged by success or failure, is called sattvic.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 18.26 (Chapter 18, Liberation through Renunciation (Moksha Sannyasa Yoga), Verse 26)