Bhagavad Gita · 18.49

असक्तबुद्धिः सर्वत्र जितात्मा विगतस्पृहः।नैष्कर्म्यसिद्धिं परमां संन्यासेनाधिगच्छति॥

asakta-buddhiḥ sarvatra jitātmā vigata-spṛihaḥ naiṣhkarmya-siddhiṁ paramāṁ sannyāsenādhigachchhati

One whose intellect is unattached everywhere, who has conquered the self, from whom desire has departed — such a one attains through renunciation the supreme state of freedom from action.

— Bhagavad Gita 18.49

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