B.G 18.26
मुक्तसङ्गोऽनहंवादी धृत्युत्साहसमन्वितः। सिद्ध्यसिद्ध्योः निर्विकारः कर्ता सात्विक उच्यते ॥२६॥
muktasaṅgo'nahaṁvādī dhṛtyutsāhasamanvitaḥ। siddhyasiddhyoḥ nirvikāraḥ kartā sātvika ucyate ॥26॥
[मुक्तसङ्गः (muktasaṅgaḥ) - free from attachment; अनहंवादी (anahaṁvādī) - without egoism; धृत्युत्साहसमन्वितः (dhṛtyutsāhasamanvitaḥ) - endowed with perseverance and enthusiasm; सिद्ध्यसिद्ध्योः (siddhyasiddhyoḥ) - in success and failure; निर्विकारः (nirvikāraḥ) - unperturbed; कर्ता (kartā) - doer; सात्विकः (sātvikaḥ) - in the mode of goodness; उच्यते (ucyate) - is said;]
(The doer who is free from attachment, without egoism, endowed with perseverance and enthusiasm, unperturbed in success and failure, is said to be in the mode of goodness.)
A person who performs their duties without attachment, ego, and remains steady in both success and failure, is considered to be acting in the mode of goodness.