Bhagwad Gita
Chapter 3, Verse 19
तस्मादसक्तः सततं कार्यं कर्म समाचर।
असक्तो ह्याचरन्कर्म परमाप्नोति पूरुषः।।3.19।।
Therefore, without being attached to the fruits of activities, one should act as a matter of duty; for by working without attachment, one attains the Supreme.