Thirukkural

Kural - 301
Where thou hast power thy angry will to work, thy wrath restrain;
Where power is none, what matter if thou check or give it rein?
He restrains his anger who restrains it when it can injure; when it cannot injure, what does it matter whether he restrain it, or not ?

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

Kural - 303
If any rouse thy wrath, the trespass straight forget;
For wrath an endless train of evils will beget.
Forget anger towards every one, as fountains of evil spring from it.

Kural - 304
Wrath robs the face of smiles, the heart of joy,
What other foe to man works such annoy?
Is there a greater enemy than anger, which kills both laughter and joy ?

Kural - 305
If thou would'st guard thyself, guard against wrath alway;
'Gainst wrath who guards not, him his wrath shall slay.
If a man would guard himself, let him guard against anger; if he do not guard it, anger will kill him.

Kural - 306
Wrath, the fire that slayeth whose draweth near,
Will burn the helpful 'raft' of kindred dear.
The fire of anger will burn up even the pleasant raft of friendship.

Kural - 307
The hand that smites the earth unfailing feels the sting;
So perish they who nurse their wrath as noble thing.
Destruction will come upon him who ragards anger as a good thing, as surely as the hand of him who strikes the ground will not fail.

Kural - 308
Though men should work thee woe, like touch of tongues of fire.
'Tis well if thou canst save thy soul from burning ire.
Though one commit things against you as painful (to bear) as if a bundle of fire had been thrust upon you, it will be well, to refrain, if possible, from anger.

Kural - 309
If man his soul preserve from wrathful fires,
He gains with that whate'er his soul desires.
If a man never indulges anger in his heart, he will at once obtain whatever he has thought of.

Kural - 310
Men of surpassing wrath are like the men who've passed away;
Who wrath renounce, equals of all-renouncing sages they.
Those, who give way to excessive anger, are no better than dead men; but those, who are freed from it, are equal to those who are freed (from death).