Kural - 561

Who punishes, investigation made in due degree,
So as to stay advance of crime, a king is he

Explanation
He is a king who having equitably examined (any injustice which has been brought to his notice), suitably punishes it, so that it may not be again committed.

Tamil Transliteration
Thakkaangu Naatith Thalaichchellaa Vannaththaal
Oththaangu Oruppadhu Vendhu.