The Noble Qur’an - Fussilat 41:34

The good deed and the evil deed cannot be equal. Repel (the evil) with one which is better (i.e. Allâh ordered the faithful believers to be patient at the time of anger, and to excuse those who treat them badly), then verily! he, between whom and you there was enmity, (will become) as though he was a close friend.

The Noble Qur’an - Al-’Imran 3:134

Those who spend [in Allâh’s Cause - deeds of charity, alms, etc.] in prosperity and in adversity, who repress anger, and who pardon men; verily, Allâh loves Al-Muhsinûn (the good­doers).

Hadith - Sahih Al-Bukhari 8.135, Narrated Abu Huraira, r.a.

Allah’s Apostle (saaws) said, “The strong is not the one who overcomes the people by his strength, but the strong is the one who controls himself while in anger.”

Hadith - Sahih Al-Bukhari 8.137, Narrated Abu Huraira, r.a.

A man said to the Prophet , “Advise me!” The Prophet said, “Do not become angry and furious.” The man asked (the same) again and again, and the Prophet said in each case, “Do not become angry and furious.”

What to do when angry

Hadith - Sahih Bukhari 8.136, Narrated Sulaiman bin Sarad, r.a.

Two men abused each other in front of the Prophet while we were sitting with him. One of the two abused his companion furiously and his face became red. The Prophet said, “I know a word (sentence) the saying of which will cause him to relax if this man says it. Only if he said, ‘I seek refuge with Allah from Satan, the outcast.’ “ So they said to that (furious) man, “Don’t you hear what the Prophet is saying?” He said, “I am not mad.”

Sayings of the Salaf

‘Abdullâh ibn Mubârak (rahimahullâh) would say, “The world is the believer’s prison. The best action in the prison is patience and control of one’s anger. The believer has no country in the world, His land will be there tomorrow in the Afterlife.”

One of the Salaf said, “One of you might see his own faults but he still loves himself. He then hates his Muslim brother on suspicion. So where is the logic?”

Hadith - Al-Tirmidhi #5145, Narrated Abu Sa’id al-Khudri, transmitted by Tirmidhi

...It is said that he (saaws) mentioned anger, saying, “Some are swift to anger and swift to cool down, the one characteristic making up for the other; some are slow to anger and slow to cool down, the one characteristic making up for the other; but the best of you are those who are slow to anger and swift to cool down, and the worst of you are those who are swift to anger and slow to cool down.” He continued, “Beware of anger, for it is a live coal on the heart of the descendant of Adam. Do you not notice the swelling of the veins of his neck and the redness of his eyes? So when anyone experiences anything of that nature he should lie down and cleave to the earth.”