From the seven hundred
कर्मण्येवाधिकारस्ते मा फलेषु कदाचनमा कर्मफलहेतुर्भूर्मा ते सङ्गोऽस्त्वकर्मणि
karmaṇy evādhikāras te mā phaleṣu kadācana mā karma-phala-hetur bhūr mā te saṅgo’stv akarmaṇi

“You have a right to your work, but never to its fruits. Let the fruit not be your motive, and do not cling to inaction either.”

Bhagavad Gita 2.47
In plain terms

The most quoted line in the Gita is working advice before it is anything else. Give the task your full care; the result belongs to a hundred causes beyond you, so let your grip on it loosen.

The second half is the part people forget: this is no licence to drift into doing nothing. The verse asks for more effort, held more lightly, at the same time.

All the verses, by the moment you need them