Chapter 4 · Knowledge and Renunciation of Action · Krishna said
Bhagavad Gita 4.15 — Act as the ancients did
एवं ज्ञात्वा कृतं कर्म पूर्वैरपि मुमुक्षुभिः। कुरु कर्मैव तस्मात्त्वं पूर्वैः पूर्वतरं कृतम् ॥
evaṃ jñātvā kṛtaṃ karma pūrvairapi mumukṣubhiḥ | kuru karmaiva tasmāttvaṃ pūrvaiḥ pūrvataraṃ kṛtam ||
Meaning
Knowing this, even the seekers of liberation in ancient times did their work. So you too should act, as the ancients did long ago.