Chapter 4, Verse 15
Part of 4: Jñāna Karm Sanyās Yog — ज्ञानकर्मसंन्यासयोगएवं ज्ञात्वा कृतं कर्म पूर्वैरपि मुमुक्षुभिः। कुरु कर्मैव तस्मात्त्वं पूर्वैः पूर्वतरं कृतम्॥
evaṁ jñātvā kṛitaṁ karma pūrvair api mumukṣhubhiḥ kuru karmaiva tasmāttvaṁ pūrvaiḥ pūrvataraṁ kṛitam
Having known this, the ancient seekers of freedom also performed action; therefore, do thou also perform action, as the ancients did in days of yore.
Knowing thus that the Self can have no desire for the fruits of actions and cannot be tainted by them, and knowing that no one can be tainted if he works without egoism, attachment and expectation of fruits, do thou perform your duty. If your heart is impure, perform actions for its purification. If you have attained AtmaJnana or the knowledge of the Self, work for the wellbeing of the world. The ancients such as Janaka and others performed actions in the days of yore. So do thou also perform action.