"I wish I didn’t say that" or "I wish I didn't do that" - How many times have we said this after reflecting on what we said or did during a moment of “anger”? We regret and then we have to apologise. How many sins have been committed because of anger.
The Prophet s.a.w knew of the harmful effects that anger can have and so when a man came to him and asked “O Messenger of Allaah, advise me,” the Messenger (peace and blessings of Allaah be upon him) said, “Do not become angry.” The man repeated his question several times and the Messenger said, “Do not become angry.” (Narrated by al-Bukhaari, 6116).
Anger is not a proof of our strength, rather it is a great weakness that we have and the Prophet s.a.w also told us "The strong one is not one who can out-wrestle others. Rather, the strong one is one who can restrain themselves when angry." (Bukhari & Muslim)
When anger overcomes us we sometimes lose control of what we say, we may utter phrases of blasphemy, we may hurt those around us or carry many other sins, and so the Messenger of Allah (s.a.w) advised us what to do:
The Prophet s.a.w said, “If you get angry, stay silent.” (Ahmad) and “If you get angry while standing, sit down…. If you get angry while sitting, lie down.”
And further the Prophet informed us that anger is from Satan, and he was created from fire, so we should extinguish anger with ritual ablutions. [Abu Dawud] When a man got angry in front of the Prophet (Allah bless him & give him peace), he told his companions, “I know some words that would make his anger leave, if he said them. They are, A`udhubillahi min al-shaykhtan (‘I seek refuge in Allah from Satan’). (Bukhari)
The righteous (al-muttaqoon) are those praised by Allaah in the Qur’aan and by His Messenger (s.a.w). Some of their characteristics is that they "spend (in Allaah’s Cause) in prosperity and in adversity, [they] repress anger, and [they] pardon men; verily, Allaah loves al-muhsinoon (the good-doers)." (Aal ‘Imraan 3:134)
And for those who restrain their anger a great reward has been promised:
Do not become angry and Paradise will be yours (Saheeh al-Jaami) and in another hadith the Prophet s.a.w tells us: "Whoever controls his anger at the time when he has the means to act upon it, Allaah will call him before all of mankind on the Day of Resurrection, and will let him choose of the Hur al-’Iyn whoever he wants." (Reported by Abu Dawud)
A’isha (r.a) reports that, “The Prophet entered while she was angry. So he rubbed the tip of my nose and said, ‘My little `A’isha. Say, ‘O Allah, forgive my sin, remove the anger in my heart, and protect me from Satan.’ (Allahumma’ Ghfirli dhanbi, wa adhhib ghaydha qalbi, wa aajirni min ash-shaytan)” (Ibn al-Sunni)
O Allah forgive our sins, remove the anger in our hearts and protect us from shaytaan - ameen