Thirukkural

அஞ்சுவ தோரும் அறனே ஒருவனை வஞ்சிப்ப தோரும் அவா.

Anjuva Thorum Arane Oruvanai Vanjippa Thorum Avaa

It is the chief duty of (an ascetic) to watch against desire with (jealous) fear; for it has power to deceive (and destroy) him