Ramayana
यमो दण्डादवध्यत्वमरोगत्वं च नित्यशः । वरं ददामि सन्तुष्ट अविषादं च संयुगे ॥ 7-36-16 ॥
Yama, well pleased, said: I grant the boon of invulnerability to my rod (of death) and perpetual freedom from disease, and freedom from despondency in battle.
english translation