Bhagavad Gita · 3.19

तस्मादसक्तः सततं कार्यं कर्म समाचर।असक्तो ह्याचरन्कर्म परमाप्नोति पूरुषः॥

tasmād asaktaḥ satataṁ kāryaṁ karma samāchara asakto hy ācharan karma param āpnoti pūruṣhaḥ

Therefore, without attachment, always perform your duty efficiently, for by performing action without attachment, a person attains the Supreme.

— Bhagavad Gita 3.19

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