Thirukkural

உற்றநோய் நோன்றல் உயிர்க்குறுகண் செய்யாமை அற்றே தவத்திற் குரு.

Utranoi Nondral Uyirkkurukan Seyyaamai Atre Thavaththir Kuru

The nature of religious discipline consists, in the endurance (by the ascetic) of the sufferings which it brings on himself, and in abstaining from giving pain to others