Bhagavad Gita · 18.9

कार्यमित्येव यत्कर्म नियतं क्रियतेऽर्जुन।सङ्गं त्यक्त्वा फलं चैव स त्यागः सात्त्विको मतः॥

kāryam ity eva yat karma niyataṁ kriyate 'rjuna saṅgaṁ tyaktvā phalaṁ chaiva sa tyāgaḥ sāttviko mataḥ

When obligatory action is performed simply because it ought to be done, O Arjuna, abandoning attachment and fruit — that renunciation is considered sattvic.

— Bhagavad Gita 18.9

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)