Tiruvalluvar

“ Sweet speech, flowing from the heart (uttered) with a cheerful countenance and a sweet look, is true virtue.
Kural-94
The men of pleasant speech that gladness breathe around,
Through indigence shall never sorrow's prey be found.
Sorrow-increasing poverty shall not come upon those who use towards all, pleasure-increasing sweetness of speech.
Kural-95
Humility with pleasant speech to man on earth,
Is choice adornment; all besides is nothing worth.
Humility and sweetness of speech are the ornaments of man; all others are not (ornaments) . ”