Kural - 317

To work no wilful woe, in any wise, through all the days,
To any living soul, is virtue's highest praise

Explanation
It is the chief of all virtues not knowingly to do any person evil, even in the lowest degree, and at any time.

Tamil Transliteration
Enaiththaanum Egngnaandrum Yaarkkum Manaththaanaam
Maanaasey Yaamai Thalai.