Kural - 302

Where power is none to wreak thy wrath, wrath importent is ill;
Where thou hast power thy will to work, 'tis greater, evil still

Explanation
Anger is bad, even when it cannot injure; when it can injure; there is no greater evil.

Tamil Transliteration
Sellaa Itaththuch Chinandheedhu Sellitaththum
Iladhanin Theeya Pira.