Once a man approached the Messenger of Allah [s] and asked: "Advise me". Then the Messenger of Allah [s] said:
"Do not be angry". The man repeated the same question and (the Prophet) again said: "Do not be angry," and continued: "He is not strong and powerful who throws people down but he is strong who withholds himself from anger."
Allah created man and gave him different psychological emotions like love, hate, fear, anger...etc. Every man feels these emotions in him according to conditions and circumstances. Thus, he likes and dislikes, becomes afraid or enraged in certain situations. Each emotion offers some profit to man if used correctly. But equally, there is the grave danger of provoking harm if they are used incorrectly. Harm will be inflicted not only on others but also will backfire on the inflictor.
For instance, Allah, the Almighty, made fear in the human soul so that he might protect himself against danger, and stay away from evil and crime. For such an occasion, fear is a good way to keep man from evil and corruption.
The faithful who fears Allah also fears committing sins and evil deeds. Consequently, he keeps to the right path by staying away from such crimes. But there is a difference between fear and cowardice. It is not right for the faithful to be a coward or to be controlled by weakness, without standing up to an aggressor or without confronting oppression, evil and corruption. Being afraid in a cowardly way only leads to being submitted to humiliation and aggression.
Anger as an emotion existing in the human soul, has a useful aim for man and can be a counterbalance to cowardice if he uses it in a correct way.
Man should be angry about an evil action or corruption in society. He should be angry for the right, for Allah alone, and he should defend good and goodness. But anger can harm himself and other people and even be changed to evil if he becomes angry for meaningless causes and does not control himself, allowing his anger to overwhelm his will. Anger then pushes man to oppress others and to commit crimes by its uncontrollable use, which is in gross disobedience to Allah.
The Messenger of Allah [s] forbids man against such anger but considers one who controls himself when he is confronted with evil sufficient to make him angry, as a man strong in will, mind and wisdom. He is more powerful than a wrestler, as his mental control is more than physical strength, and defeats evil and aggression not only in others but also in himself.
The man who can control himself when angry, and prevent himself from doing harm to others or oppressing them or punishing them, has a will of iron and is of exalted character. He couples pushing problems away and alleviating harm from himself with spreading the spirit of love, forgiveness and tolerance among people.
Indeed, Allah loves those who control their anger and He forgives those who do not seek revenge or punishment.
Certainly, Allah, the Exalted is All-Forgiving Who forgives His servants and tolerates them and He also loves His servants to forgive each other, to tolerate each other and not be vindictive to each other.
If a man wrongs another man or makes a mistake, and he repents, then Islam recommends forgiving such a man and not punishing him, because Allah is All-Pardoning and He loves those who pardon people.
1. Anger, like fear, is a psychological condition, and cause of evil and aggressive actions.
2. One who does not control his anger loses control of his mind. The enraged man cannot control his actions, and harms and hurts himself and others.
3. A faithful should have a strong will not to become angry over everything but only when he sees evil deeds or corruption, which he should try to reform.
4. A believer is one who forgives and tolerates people's mistakes because Allah loves those who forgive others and will reward them on the Day of Resurrection.
 Harrani, Tuhaf al-Uqul an aal al-Rasul, p.33, 5th Edition.