Kural - 641

A tongue that rightly speaks the right is greatest gain,
It stands alone midst goodly things that men obtain

Explanation
The possession of that goodness which is called the goodness of speech is (even to others) better than any other goodness.

Tamil Transliteration
Naanalam Ennum Nalanutaimai Annalam
Yaanalaththu Ulladhooum Andru.