Bhagavad Gita 18.49

असक्तबुद्धि: सर्वत्र जितात्मा विगतस्पृह: ।
नैष्कर्म्यसिद्धिं परमां संन्यासेनाधिगच्छति ॥

asakta-buddhi: sarvatra jitātmā vigata-spṛha:
naiṣkarmya-siddhiṃ paramāṃ sannyāsenādhigacchati – 49

With dis-attached intelligence in all situations, one who is self-regulated and free of cravings, attains the supreme perfection of naishkarmya (non-doership) through sannyāsa (renunciation).