The Meaning of Anger
Ghadab linguistically: is the opposite of pleasure and contentment (rida). A ghadbah is a solid rock. They say from that it was later used to mean anger due to its intense harshness.  Maqayis al-Lughah, Ibn Faris (4/428); Lisan al-`Arab, Ibn Manzur (1/648); Taj al-`Arus, Murtada al-Zabidi (3/485).
Ghadab technically: is the heart’s blood boiling inciting the warding off of the cause of harm, or out of vindication for what harm has already taken place.  Jami` al-`Ulum wa al-Hikam, Ibn Rajab (1/396). The Difference between Anger and Some Other Characteristics  al-Furuq al-Lughawiyyah, al-`Askari (p. 16); al-Mufradat, al-Raghib (p. 64); Sharh Hadith Labbayk, Ibn Rajab (p. 103).
● The Difference between Anger and Wrath (Sakhat)
Anger may manifest from the minor to the senior as well as from the senior to the minor. Wrath, however, may only manifest from a senior to a minor. It may be said that a ruler was wrathful at his subject, but not that the subject was wrathful at his ruler. Anger may be used for both. If sakhat is used transitively by itself, it is the antonym of pleasure, i.e. displeasure. That is: radiyahu wa sakhitahu. If it is used transitively with `ala (upon), then it is referring to intense anger and outrage - wrath.
● The Difference between Anger and Rage (Ghayz)
One may be enraged at himself, but not angry. Anger is wishing harm upon whom one is angry with, so one cannot wish harm for oneself. Rage is closer to the general meaning of anguish (ghamm).Prohibition of Anger in the Prophetic Sunnah
❖ Abu Hurayrah, Allah be pleased with him, narrated that a man said to the Prophet ﷺ: “Advise me.” He ﷺ replied: “Do not get angry.” The man kept repeating his request, and he ﷺ kept saying: “Do not get angry.”  Reported by al-Bukhari (6116).
❖ Sulayman ibn Sard, Allah be pleased with him, said: “Two men cursed each other whilst we were sitting with the Prophet ﷺ, one of them cursing the other angrily, his face turning red. The Prophet ﷺ said: ‘I know a statement that, if he says it, he will no longer feel as he does: “I seek refuge in Allah from the forsaken devil.”’ So they said to the man: ‘Do you not hear what the Prophet ﷺ said?’ He said: ‘I am not a crazy person.’”  Reported by al-Bukhari (6115) and the wording is his, as well as Muslim (2610). Quotes of the Predecessors and Scholars on Dispraising Anger  Jami` al-`Ulum wa al-Hikam, Ibn Rajab (1/373, 368).
❖ `Umar ibn `Abd al-`Aziz said: “The one who is saved from whimsical desires, anger, and greed is truly successful.”
❖ al-Hasan said: “There are four traits that if one has Allah will save him from the devil and make him unlawful for the Fire: whoever controls himself at moments of temptation, fear, desire, and anger.”
❖ Ja`far ibn Muhamad said: “Anger is the key to all evil.”Categories of Anger
Blameworthy anger: is the type of anger that is prohibited and forbidden in the aforementioned narration. It is an evil character trait as it allows one’s intellect and religiosity to go out of their composure, such that one can no longer think straight nor choose wisely.  Mukhtasar Minhaj al-Sadiqin, Ibn Qudamah (p. 232). Praiseworthy anger: is for the sake of Allah, honoured and majestic, when His sanctity is desecrated, as well as having anger against the disbelievers, hypocrites, tyrants, and despots. Impacts and Harms of Blameworthy Anger
Among the apparent impacts of anger are: one’s changing colour, shaking limbs, irrational action, instability in movement and speech. The jaw is clenched, the cheeks redden, the nostrils flare, and one’s appearance completely alters. If the angry person saw themselves in that state, they would calm down out of shame of their ugly appearance. Their internal ugliness is greater still than their manifest one, for the external is the manifestation of the internal, so the ugliness of the former is due to the ugliness of the latter. This is anger’s bodily consequences.
As for its impacts on the tongue: then all sorts of ugly words come out from it, like cursing, obscenity, and other than those which any rational person would have shame to utter at any time. Likewise, once a person calms, they regret what they said. Their speech is not ordered nor is its meaning organised. The very annunciation is incoherent.
As for its impacts on the limbs: then striking and what exceeds it, to the point of murder when able. If one’s raging fury persists, one may end up tearing his garments, striking himself and others, even animals, and breaking up and throwing things around him. He moves around like a drunkard, or lost madman. He may fall to the ground and helplessly cease from moving, being overcome by something akin to fainting from the intensity of his rage.
As for its impacts on the heart: then malice and spite against the person one is angry with, and envying him. Gloating at him, being upset at his happiness, disclosing his secrets, uncovering his hidden valuables, and mocking him. All of these are forms of ugliness.  al-Zawajir, Ibn Hajar al-Haytami (1/95), with adaptation. Examples of the Guidance of the Prophet ﷺ, Companions, and Predecessors at Moments of Anger
❖ Hind ibn Abi Halah narrates the traits of the Prophet ﷺ saying: “... The worldly life and its affairs, though if the truth is in question, he becomes unrecognisable. Nothing would do away with his anger until he gives it the truth victory, and he is never angered for the sake of his self, nor does he seek its victory…”  Reported by al-Tabarani (22/155) (414) and al-Bayhaqi in Shu`ab al-Iman (1362). Ibn Hibban said in al-Thiqat (2/145): “One cannot have a restful heart with its chain of transmission.” al-`Iraqi said in Takhrij al-Ihya’ (2/442) and al-Haythami in Majma` al-Zawa’id (8/276): “Its chain has unnamed persons.” al-Albani severely weakened it in Mukhtasar al-Shama’il (6).
❖ It is narrated that a man said to `Umar, Allah be pleased with him: “Take heed, son of al-Khattab! By Allah, you neither give us sufficient provision nor judge among us with justice.” Thereupon `Umar became so furious that he got up for him, but al-Hurr said: “Commander of the Faithful, Allah said to His Prophet ﷺ: ‘Take to pardoning and command what is right: pay no attention to the ignorant.’ al-A`raf: 199. This is one of the ignorant.” The narrator said: “By Allah, `Umar did not overlook that verse when al-Hurr recited it before him; he observed Allah's Book strictly.”  Reported by al-Bukhari (4642).
❖ `Umar ibn `Abd al-`Aziz was angry on a particular day, so his son `Abd al-Malik said to him, Allah have mercy upon them both: “Commander of the Faithful, you are who you are, with what Allah favoured you with, and yet you are angry like this?” He replied: “Do you not anger, `Abd al-Malik?” `Abd al-Malik said: “What use then is the expanse of my chest if I do not reside therein?!”  Jami` al-`Ulum wa al-Hikam, Ibn Rajab (1/366). Causes of Anger
Vanity, haughtiness, dispute, shouting, joking, getting lost, injustice, mockery, seeking what is competed over, envy, and vindictiveness.  al-Dhari`ah ila Makarim al-Shari`ah, Ibn Rajab (1/366). Opposition, treachery, sternness, covetousness of wealth and status. These are all evil morals, dispraised by the Law.  Mukhtasar Minhaj al-Qasidin, Ibn Qudamah (p. 233). Curing Anger
Ritual ablution. Sitting down if one is standing, and lying down if one is sitting. To adhere to the advice of the Prophet ﷺ: “Do not get angry.”  Reported by al-Bukhari (6116). Controlling the self from being inhibited by anger. Seeking refuge in Allah from the forsaken devil.  Zad al-Ma`ad, Ibn al-Qayyim (2/463). Silence. Dispraise of Anger in Poetry
The poet said:
“I have not seen a virtue perfected but by enacting it,
Nor have I seen sound intellect but through etiquette.
When I put my enemies to test, I did not come across
An enemy to intellect that is more hostile than anger.”  Rawdat al-`Uqala’ wa Nuzhat al-Fudala’, al-Busti (p. 139).