Bhagavad Gita 2.47
कर्मण्येवाधिकारस्ते मा फलेषु कदाचन। मा कर्मफलहेतुर्भूर्मा ते सङ्गोऽस्त्वकर्मणि।।2.47।।
karmaṇyevādhikāraste mā phaleṣu kadācana| mā karmaphalaheturbhūrmā te saṅgo'stvakarmaṇi||2.47||
karmanyevadhikaraste ma phaleshu kadacana ma karmaphalaheturbhurma te sango'stvakarmani2.47
Meaning
You have a right to perform your duty, but you are not entitled to the fruits of your actions. Never consider yourself to be the cause of the results, yet do not be attached to inaction either. This is the essence of Karma Yoga.
तेरा कर्म पर ही अधिकार है, फलों पर कभी नहीं। तू कर्म के फल का हेतु मत बन और अकर्म में भी तेरी आसक्ति न हो।
This is verse 47 of 72 in Chapter 2 (Sankhya Yoga) of the Bhagavad Gita.