Kural - 97

The words of sterling sense, to rule of right that strict adhere,
To virtuous action prompting, blessings yield in every sphere

Explanation
That speech which, while imparting benefits ceases not to please, will yield righteousness (for this world) and merit (for the next world).

Tamil Transliteration
Nayan Eendru Nandri Payakkum Payaneendru
Panpin Thalaippiriyaach Chol.