Kural - 710

The men of keen discerning soul no other test apply
(When you their secret ask) than man's revealing eye

Explanation
The measuring-rod of those (ministers) who say "we are acute" will on inquiry be found to be their (own) eyes and nothing else.

Tamil Transliteration
Nunniyam Enpaar Alakkungol Kaanungaal
Kannalladhu Illai Pira.