Bhagavad Gita · 3.30

मयि सर्वाणि कर्माणि सन्न्यस्याध्यात्मचेतसा।निराशीर्निर्ममो भूत्वा युध्यस्व विगतज्वरः॥

mayi sarvāṇi karmāṇi sannyasyādhyātma-chetasā nirāśhīr nirmamo bhūtvā yudhyasva vigata-jvaraḥ

Surrendering all actions to Me with a mind fixed on the Self, free from desire and possessiveness, fight — free from mental fever.

— Bhagavad Gita 3.30

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