Views of the salaf and Sunni scholars concerning the repentance of one who kills someone deliberately and unlawfully
Question

Can the one who kills someone deliberately repent, or is it not possible for him to repent? What are the views of the salaf and Sunni scholars concerning that?
Praise be to Allah.The fuqaha’ differed as to whether the repentance of one who kills someone deliberately and unlawfully may be accepted.
The majority of fuqaha’ are of the view that the one who kills someone deliberately and wrongfully may repent (and his repentance may be accepted), as is also the case for those who commit other major sins, because of the texts which speak specifically of that, as well as the general texts which speak of the repentance of all people being accepted. That includes the verses in which Allah, may He be exalted, says (interpretation of the meaning):
“And those who invoke not any other ilaah (god) along with Allah, nor kill such person as Allah has forbidden, except for just cause, nor commit illegal sexual intercourse __and whoever does this shall receive the punishment.
69. The torment will be doubled to him on the Day of Resurrection, and he will abide therein in disgrace;
70. Except those who repent and believe (in Islamic Monotheism), and do righteous deeds; for those, Allah will change their sins into good deeds, and Allah is Oft‑Forgiving, Most Merciful
71. And whosoever repents and does righteous good deeds; then verily, he repents towards Allah with true repentance”
[al-Furqaan 25:68-70]
“And whoever kills a believer intentionally, his recompense is Hell to abide therein, and the Wrath and the Curse of Allah are upon him, and a great punishment is prepared for him”
[an-Nisa’ 4:93].
The general meaning of the latter verse is to be understood in the light of the specific meaning of the verses from al-Furqaan. So what is meant is: his recompense will be Hell, to abide therein forever, except for the one who repents.
Because the repentance of the disbeliever, by virtue of his entering Islam, is accepted according to scholarly consensus, it is more apt that the repentance of the murderer should be accepted.
The wording used by the fuqaha’ differed with regard to what conditions there are for this repentance to be accepted and what may be waived as a result.
The Hanafis said that the repentance of the murderer, in the sense of praying for forgiveness and showing regret only, is not valid; rather it depends on the approval of the heirs of the victim. If the killing was done deliberately, then it is essential to allow them to exact lawful retribution (qisaas), so if they wish, they may kill him, or if they wish, they may pardon him, and if they pardon him then his repentance is accepted and he is absolved of sin in this world.
The Maalikis spoke in general terms of the acceptance of the repentance of one who has killed deliberately. Al-Qurtubi said: This is the view of Ahl as-Sunnah, and it is the correct view.
The Shaafa‘is said: The gravest of major sins after disbelief is wrongful killing, but by means of lawful retribution or pardon, no one will have any claim against him in the hereafter. However, the right of Allah, may He be exalted, remains and cannot be waived except by means of sound repentance. Merely allowing lawful retribution to be carried out on him is not sufficient with regard to the right of Allah, unless it is accompanied by sincere regret for the sin and resolve not to do it again.
The Hanbalis said: The right of the victim in the hereafter is not waived merely by repentance, as is the case with all other rights. Based on that, the victim will take from the hasanaat (good deeds) of the killer, to a degree commensurate with the extent to which he was wronged.
If legal retribution is exacted on behalf of the victim from the killer, or the victim’s heirs excuse the killer from legal retribution, can the victim demand retribution in the hereafter? There are two points of view, as mentioned by the author of al-Furoo‘.
Ibn ‘Abbaas and Zayd ibn Thaabit (may Allah be pleased with them) differed from the majority concerning the acceptance of the killer’s repentance. They were of the view that the repentance of one who killed deliberately and wrongfully will not be accepted, because Allah, may He be exalted, says (interpretation of the meaning): “And whoever kills a believer intentionally, his recompense is Hell to abide therein, and the Wrath and the Curse of Allah are upon him, and a great punishment is prepared for him” [an-Nisa’ 4:93]. Ibn ‘Abbaas (may Allah be pleased with him) was asked: Can one who killed a believer deliberately repent? He said: No; (he has nothing) but Hell. Then he recited the verse quoted above, which was the last thing to be revealed concerning this matter and was not abrogated by anything. Moreover, this verse is a statement of what will happen, and such statements are not subject to abrogation or alteration, because Allah states about what will happen cannot be anything but true.
End quote from al-Mawsoo‘ah al-Fiqhiyyah (41/30-31)
Ibn Jareer at-Tabari (may Allah have mercy on him) said:
With regard to the words “his recompense is Hell to abide therein”, the commentators differed as to what is meant here:
-1-
Some of them said that what is meant is that his recompense will be Hell, if He decrees that he is to be punished.
Among those who held this view were Abu Majlaz Laahiq ibn Humayd and Abu Saalih.
-2-
Others said that what is meant is a particular man who had become Muslim, then he apostatised from Islam and killed a believing man. They said: What the verse means is: whoever kills a believer deliberately, believing it to be permissible to kill him, then his recompense will be Hell, to abide therein forever.
This was narrated by ‘Ikrimah, the freed slave of Ibn ‘Abbaas.
-3-
Others said that what is meant is: unless he repents.
Among those who held this view was Mujaahid ibn Jabr.
-4-
Others said that this makes the warning of Allah inevitable for the one who kills a believer deliberately, regardless of who the killer is, and He has not allowed him the opportunity to repent from his deed. They said: So everyone who kills a believer deliberately will have what Allah has warned him about of punishment and eternity in Hell, and he has no option of repentance. They said: This verse was revealed after the passage in Soorat al-Furqaan.
Among those from whom this was narrated were Ibn Mas‘ood, Ibn ‘Abbaas, Zayd ibn Thaabit, and ad-Dahhaak ibn Muzaahim.
Ibn Jareer said:
The most correct view concerning that is the view of those who said that what is meant is: Whoever kills a believer deliberately, his punishment, if he is punished, will be Hell, to abide therein forever, but Allah may forgive and bestow His grace upon those who believe in Him and His Messenger, in which case He will not punish them by causing them to abide therein for eternity.  Rather He, may He be glorified, may either forgive him by His grace, and not admit him to Hell, or He may add admit him therein, then bring him forth from it by virtue of His mercy, because of His promise to His believing slaves in the verse (interpretation of the meaning): “Say: O ‘Ibaadi (My slaves) who have transgressed against themselves (by committing evil deeds and sins)! Despair not of the Mercy of Allah, verily, Allah forgives all sins” [al-Zumar 39:53].
End quote from Tafseer at-Tabari (9/61-69)
Ibn Katheer (may Allah have mercy on him) said:
The view of the majority of the earlier and later generations of the ummah is that the killer may repent to his Lord, may He be glorified and exalted, and if he repents, turns to Allah, humbles himself before Him and does righteous deeds, Allah will turn his evil deeds into good deeds, and He will compensate the victim for the wrong that was done to him, and He will give him enough so that he will no longer seek redress from his killer.
End quote from Tafseer Ibn Katheer (2/380)
See also: Madaarij as-Saalikeen (1/392-399); Tafseer Ibn Katheer (6/124-130)
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:
If you say: What do you say about the saheeh report from Ibn ‘Abbaas (may Allah be pleased with him) that the murderer cannot repent?
The answer is one of two things:
Either Ibn ‘Abbaas (may Allah be pleased with him) thought it unlikely that one who killed deliberately can repent, and he thought that he would not be helped and guided to repent, and if he is not helped and guided to repent, then this sin is not waived from him; rather he will be brought to account for it,
or it may be said that what Ibn ‘Abbaas meant was that his repentance will not waive the rights of the one who was killed.
End quote from Majmoo‘ Fataawa wa Rasaa’il Ibn ‘Uthaymeen (8/222)
It was also narrated from Ibn ‘Abbaas in a saheeh report that he (the one who kills another person deliberately) may repent (and his repentance may be accepted). At-Tabari (9/67) narrated that he said: There is no forgiveness for the murderer, unless he asks Allah for forgiveness.
Shaykh al-Albaani (may Allah have mercy on him) said: This was narrated by Ibn Jareer with a jayyid isnaad. Perhaps he meant that he will not be forgiven, according to his first view, then he corrected himself and said: unless he asks Allah to forgive him.
End quote from as-Silsilah as-Saheehah (6/298)
And Allah knows best.