The Meaning of Cruelty, Harshness, and Coarseness
Qaswah linguistically: is rigidity in all matters. Qasa qalbuhu qaswatan wa qasawatan wa qasa’an is referring to the heart becoming harsh and hard.  Lisan al-`Arab, Ibn Manzur (15/10).
Qaswah technically: is the shrinking and disappearance of softness, mercy.  The previous source.
Ghilzah linguistically: ghilz is the antonym to delicateness (riqqah) in character, disposition, action, rationale, and livelihood.  The previous source (7/449).
Ghilzah technically: is having a cruel heart, a lack of pity, and no insurgency to do good.  Fath al-Qadir, al-Shawkani (1/451).
Fazazah linguistically: rajulun fazzun ghu fazazah, meaning one is rude in his rationale and is uncouth. Fazazah and fazaz is coarse language.  al-`Ayn, al-Khalil (8/153).
Fazazah technically: he who is fazz is coarse in his dealings, has poor manners, and is harsh with his words.  al-Qamus al-Muhit, al-Fayruzabadi (p. 697). The Difference between Harshness and Coarseness and Some Other Characteristics  al-Furuq al-Lughawiyyah, al-`Askari (p. 429); Tilbat al-Talabah, al-Nasafi (3/316); Zad al-Masir, Ibn al-Jawzi (p. 340); Tafsir al-Razi (9/407); Tafsir Ibn `Abd al-Salam, `Izz al-Din ibn `Abd al-Salam (p. 697); al-Ruh, Ibn al-Qayyim (1/241).
● The Difference between Harshness and Coarseness
Some see them as equal in meaning, such as al-`Izz ibn `Abd al-Salam. Others view them as different from various facets: Ibn `Abbad’s view is harshness is in word while coarseness is in deed. One who is coarse (fazz) has poor mannerisms, but one who has a harsh heart is he whose heart is not affected by anything. Coarseness is roughness of heart, whereas harshness is cruelty of heart.
● The Difference between Cruelty and Hardness (Salabah)
Cruelty is used to refer to that which is unaccepting of treatment. It is for this reason that a heart is described as such if it is not rigid.Dispraise of Cruelty, Harshness, and Coarseness in the Qur’an and Sunnah
❖ Allah, exalted, says: “Even then your hearts became hardened like a rock or even harder, for some rocks gush rivers; others split, spilling water; while others are humbled in awe of Allah. Allah is never unaware of what you do.” al-Baqarah: 74. al-Sa`di said: “‘Hardened’ refers to their hearts becoming harsher and coarser, such that it is unaffected by admonishment.”  Taysir al-Karim al-Rahman fi Tafsir Kalam al-Mannan, al-Sa`di (p. 55).
❖ Allah, exalted, says: “It is out of Allah’s mercy that you Prophet have been lenient with them. Had you been cruel or hard-hearted, they would have certainly abandoned you.” Al `Imran: 159.
❖ Ibn Mas`ud, Allah be pleased with him, said that the Prophet ﷺ said, pointing with his hand to Yemen: “Faith is there,” twice, “Cruelness and harsh-heartedness is found among the callous camel herders whence the devil’s two horns originate, in Rabi`ah and Mudar.”  Reported by al-Bukhari (3302) and Muslim (51).
❖ Harithah ibn Wahb, Allah be pleased with him, narrated that he heard the Prophet ﷺ saying: “Shall I tell you of the inhabitants of the Garden? They comprise every poor humble person, if he swears upon Allah, Allah would fulfill their promise. The inhabitants of the Fire comprise every violent, cruel `utull, prideful person.”  Reported by al-Bukhari (6657) and Muslim (2853). Ibn `Uthaymin said: “The `utull is the every stern, coarse person who does not soften to the truth or the people.”  Kutub wa Rasa’il Ibn `Uthaymin, Majalis Shahr Ramadan [Ramadan Sittings] (p. 155). Quotes of the Predecessors and Scholars on Cruelty
❖ Malik ibn Dinar: “Four are the signs of suffering: a cruel heart, a dry eye, wishful thinking, and covetousness with the worldly life.”  al-Zuhd wa Sifat al-Zahidin, Ibn al-A`rabi (1/47).
❖ Hudhayfah al-Mar`ashi said: “There is no one trialled with anything greater than a cruel heart.”  Hilyat al-Awliya’, Abu Nu`aym (10/168).
❖ Ibn al-Qayyim said: “A slave is not struck with a punishment worse than a cruel heart and furtherance from Allah. The Fire is created to melt hard hearts. The furthest hearts from Allah are the cruel ones.”  al-Fawa’id, Ibn al-Qayyim (1/97). Permissible Forms of Cruelty, Harshness, and Coarseness  Adapted from: al-Adhkar, al-Nawawi (1/280); Min Sifat al-Da`iyah Mura`at Ahwal al-Mukhatabin, Fadl Ilahi (p. 180).
In fighting for the sake of Allah. Arguing with the aggressive oppressor from the People of the Book. A woman talking with foreign men out of need. When establishing penal codes. When there is stubborn ridicule of the religion. When a person breaks the Law when it is unbecoming and unexpected of him to do so. Signs of Cruelty of Heart and Harshness  See: Ihya’ `Ulum al-Din, al-Ghazali (4/484); Fayd al-Qadir, al-Manawi (1/122) and (4/482).
Being unaffected by the Noble Qur’an. Having rigid eyes that do not tear for the fear of Allah. Not taking heed from death, laughing in the presence of graves. Arrogance, not accepting truth: “a cruel heart does not accept truth even if its evidences are plenty.”  Fayd al-Qadir, al-Manawi (1/122). Being uncaring to what befalls others of evil, even finding glee in it. Impacts of Cruelty of Heart, Harshness, and Coarseness  See: Shifa’ al-`Alil, Ibn al-Qayyim (1/106).
Altering statements from their rightful places and meanings. This is a fruit of misunderstanding and ill intention, both of which are a result of a cruel heart. Forgetting what one was reminded of - this is leaving what one is commanded to do in speech and action. The perishing of bounties, the befalling of calamitous and destructiveness tribulation. The cruel heart is the weakest in faith, swiftest to accept doubts and fall into trial and misguidance. It is a cause for going astray and incurring Allah’s curse, wrath, and punishment. Waning in worship, falling into the unlawful, abandoning enjoinment of good and forbiddance of evil. Alienation, constant fear, frowning face, and depression.
Repulsion between hearts, and hatred and dislike becoming rife.Causes of Cruelty of Heart, Harshness, and Coarseness  See: Ihya’ `Ulum al-Din, Abu Hamidal-Ghazali; `Umdat al-Qari, al-`Ayni (15/274); Fayd al-Qadir, al-Manawi (5/417); Bariqah Mahmudiyyah, Abu Sa`d al-Khadimi (4/97).
Heedlessness of Allah’s remembrance, reflecting over the Qur’an, and contemplating Allah’s cosmic signs. Sinning a lot. Being loose with performing obligatory acts of worship and desecration of prohibitions. Busying oneself with the worldly life, immersing in its pursuit and competing over it. Prolonged wishful thinking. Blameworthy uninhibited consumption with what is permissible. Mixing with the people plentifully without specific purpose or benefit. Not having mercy with the creation, nor being beneficent with them. Means to Desisting from Cruelty of Heart, Harshness, and Coarseness
Supplication. Reciting the Qur’an and contemplating its verses. Abundantly remembering Allah, honoured and majestic. Abundantly seeking forgiveness and repenting. Remembering death and visiting graves. Accompanying the righteous, sitting with them, and reading the biographies of the Righteous Predecessors. Being good in treating the weak. Stories about Cruelty, Harshness, and Coarseness
❖ al-Rabi` ibn Khuthaym would visit one of his deceased friend’s houses at night if he found his heart hard. He would say: “So-and-so, son of so-and-so; so-and-so, son of so-and-so...” Then he would say: “If only I knew what you did and what has been done to you!” he would then cry until his tears flowed. He would be known to have done so from his likeness.  Shu`ab al-Iman, al-Bayhaqi (7/19).
❖ Malik said: “Muhammad ibn al-Munkadir was the master of reciters. He would often weep upon hearing prophetic narrations. When I would find harshness in myself, I would visit him and look at him and find admonishment in that.”  al-Tamhid, Ibn `Abd al-Barr (12/222). Cruelty of Heart, Harshness, and Coarseness in Poetry
The poet said regarding not being thankful for beneficence and bounty:
“Whoever is not thankful for bounties is coarse
And harsh natured, no admonishment benefited him.
Gratitude for what is bestowed is preserving it;
Man misses none of his share through incapacity.”  Hilyat al-Bashar fi Tarikh al-Qarn al-Thalith `Ashar, `Abd al-Razzaq al-Baytar (p. 1291).