Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Anger is a very serious disease, and Islam warns Muslims against its evil consequences. The Prophet (peace and blessings be upon him) prescribed a remedy for the person in a state of anger, instructing him to sit down or lie down until he cools off.
Also, he told us that performing wudu’ is a good way to put out the “fire” of one’s anger. May Allah forgive us all and protect us from Hellfire, amen!
Answering your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Before giving you some du`a’s I would like to give you some tips gleaned from Imam Al-Ghazali.
In order to control your anger, you must do two things:
First, you should ask yourself why, when, and how you are getting angry and control the circumstances that create such situations. By directing your thoughts in this way, you can often control your anger.
So, condition yourself to ask questions such as the following: Why am I getting angry? What is the big deal about reacting to something that happened in the past? Can I change it now?
If the milk is already spilled, how is my anger going to help to bring it back? What benefit can I gain by reacting in anger? Is there anything far more beneficial I can do instead?
Furthermore, think of all the harmful effects of anger if it is not controlled. In fact, there is nothing more destructive than anger if it leads to violence or inflicting verbal or emotional abuse on people.
So, condition yourself to think of the destructive consequences of anger until you learn to associate anger with pain, ugliness and suffering. In this way, you will be better able to take control of your anger and make sure that it is not expressed in a harmful way.
Second, as soon you find yourself becoming angry, channel your energy in positive ways by immediately taking the following steps:
A`oodhu billahi mina ash-shaytaani ar-rajeem.
(I seek refuge in Allah from Satan the accursed) three times, and walk immediately to the washroom and perform ablutions with cool water and pray two rak`ahs.
Alternately, you can repeat the above words, and go for a walk or take some deep breaths and do some minor exercises to release the tension and relax.
Finally, here are a few du`a’s you should recite and meditate upon consistently:
Allaahumma innee a`oodhu bika min hamazaati ash-shayaateen; wa a`oodhu bika rabbi an yahdhuroonee.
(O Allah, I seek refuge in You from the whisperings of devils; and I seek refuge in You from their presence around me).
Astaghfiru Allah (I ask Allah for forgiveness) three times.
Rabbi qinee sharra nafsee; rabbi qinee sharra sam`ee; rabbi qinee sharra basaree; rabbi qinee sharaa lisaanee.
(My Lord, save me from the evils of my own self; my Lord, save me from the evils of my hearing; my Lord, save me from the evils of my seeing; my Lord, save me from the evils of my tongue.)
You can also simply make the following tasbeeh:
Subhaan Allah, al-hamdu lillah, laa ilaha illa Allah, wa laa hawla wa laa quwwata illa bi-llah.
(Sublime is Allah; praise be to Allah; there is no god but Allah; there is no power or strength except by the will of Allah).
Allah Almighty knows best.
Excerpted, with slight modifications, from: www.islam.ca