Bhagavad Gita · 18.18

ज्ञानं ज्ञेयं परिज्ञाता त्रिविधा कर्मचोदना।करणं कर्म कर्तेति त्रिविधः कर्मसंग्रहः॥

jñānaṁ jñeyaṁ parijñātā tri-vidhā karma-chodanā karaṇaṁ karma karteti tri-vidhaḥ karma-saṅgrahaḥ

Knowledge, the object of knowledge, and the knower — these three motivate action. The instrument, the action, and the doer — these three constitute the basis of action.

— Bhagavad Gita 18.18

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)