Kural - 93

With brightly beaming smile, and kindly light of loving eye,
And heart sincere, to utter pleasant words is charity

Explanation
Sweet speech, flowing from the heart (uttered) with a cheerful countenance and a sweet look, is true virtue.

Tamil Transliteration
Mukaththaan Amarndhuinidhu Nokki Akaththaanaam
Inso Linadhe Aram.