Kural - 460

Than good companionship no surer help we know;
Than bad companionship nought causes direr woe

Explanation
There is no greater help than the company of the good; there is no greater source of sorrow than the company of the wicked.

Tamil Transliteration
Nallinaththi Noongun Thunaiyillai Theeyinaththin
Allar Patuppadhooum Il.