Bhagavad Gita

ಸಕ್ತಾಃ ಕರ್ಮಣ್ಯವಿದ್ವಾಂಸೋ ಯಥಾ ಕುರ್ವಂತಿ ಭಾರತ।
ಕುರ್ಯಾದ್ ವಿದ್ವಾಂಸ್ತಥಾಸಕ್ತಶ್ಚಿಕೀರ್ಷುರ್ಲೋಕಸಂಗ್ರಹಮ್॥೨೫॥
saktāḥ karmaṇyavidvāṃso yathā kurvaṃti bhārata|
kuryād vidvāṃstathāsaktaścikīrṣurlokasaṃgraham||25||

Gist of the sloka:
O Bharatha, those who have no understanding of the result, renunciate karma but still undertakes it, similarly, those who are aware of the renunciate karmas, need to do it. One should have no attachment with the results of the action and should set the example for the world.
Those who are ignorant perform actions which are attached to the rewards. Whereas, those who are aware of the proper way [karma detached from results] have to perform karma [karma yoga]. One should perform his duties with detachment to the results believing that “I will be satisfied with whatever the Lord gives me and I only do it as a service to the Lord”. This is real karma yoga.