Kural - 814

A steed untrained will leave you in the tug of war;
Than friends like that to dwell alone is better far

Explanation
Solitude is more to be desired than the society of those who resemble the untrained horses which throw down (their riders) in the fields of battle.

Tamil Transliteration
Amarakaththu Aatrarukkum Kallaamaa Annaar
Thamarin Thanimai Thalai.