An-Nisa: 92-93
"And it is not for a believer..."
It is not correct for him, nor is it upright, nor does it befit his state. Similar to His saying: "It is not for a prophet to betray" (Al-Imran: 161), and "It is not for us to return to it" (Al-A'raf: 89).
"...to kill a believer..."
Initiating the act without it being a legal retribution (qisas).
"...except by mistake."
Except in the manner of a mistake. If you ask: "What is the grammatical case of khata'an (mistake)?" I say: It is a maf'ul lahu (causative object), meaning: It is not appropriate for him to kill him for any reason except for the sake of a mistake alone. It is also permissible for it to be a hal (state), meaning: He does not kill him in any state except in the state of a mistake. It may also be an adjective for the verbal noun, meaning: "except for a killing that is a mistake."
The meaning is that it is the nature of a believer that the killing of a believer should be negated from him entirely, unless it occurs by mistake without intent—such as shooting at a disbeliever and hitting a Muslim, or shooting at a person thinking he is a disbeliever, only to find he is a Muslim. It is recited as khata' (with a long vowel) and khata (like 'ama, with a lightened hamza).
[Historical Context]
It is narrated that 'Ayyash ibn Abi Rabi'ah, the maternal brother of Abu Jahl, embraced Islam and migrated to Medina fearing his people before the Prophet (ﷺ) migrated. His mother swore she would neither eat nor drink, nor would a roof shade her, until he returned. Abu Jahl and Al-Harith ibn Zayd went to him while he was in a fortress. Abu Jahl killed him (in spirit/status) by saying, "Does not Muhammad urge you to maintain kinship? Return and honor your mother while remaining on your religion." He came down and went with them. When they were far from Medina, they bound him and each lashed him one hundred times. 'Ayyash said to Al-Harith, "This is my brother, but who are you, O Harith? I swear to God, if I find you alone, I will kill you." They brought him to his mother, and she swore she would not untie his bonds until he apostatized. He did so. Later, he migrated and became a Muslim. Al-Harith also became a Muslim and migrated. 'Ayyash met him at the back of Quba, not knowing he had become a Muslim, and attacked and killed him. Then he was informed of his Islam. He came to the Prophet (ﷺ) and said, "I killed him without knowing of his Islam," and this verse was revealed.
"Then the freeing of a believing slave"
He must free a slave. Tahrir (freeing) is emancipation. Hurr (free) and 'atiq (emancipated) are noble, for nobility is in the free, just as baseness is in the slaves. From this comes the term 'ataq for horses and birds (meaning the noble ones). Hurr al-wajh (the face's freedom) is its most noble part. Calling a base person a "slave" is common. 'Abd al-fi'l (slave of action) means base in action. Raqaba (neck) is an expression for a soul, just as it is expressed as "head" when they say, "So-and-so owns such-and-such heads of slaves."
The intended meaning of "believing slave" is any slave who is under the rule of Islam, according to the majority of scholars. Al-Hasan said: "Only a slave who has prayed and fasted suffices; a young child does not." Al-Shafi'i drew an analogy to the zihar expiation, thus requiring faith. It is said: Since he removed a believing soul from the living, he is obligated to enter a soul like it into the ranks of the free, because releasing it from the shackles of slavery is like giving it life, as the slave is prevented from the actions of the free.
"...delivered to his family"
Paid to his heirs to be divided as they divide the inheritance. There is no difference between it and the rest of the estate in any matter; debts are paid from it, and wills are executed. If no heir remains, it goes to the Public Treasury (Bayt al-Mal), for the Muslims take the place of the heirs, as the Prophet (ﷺ) said: "I am the heir of him who has no heir."
'Umar (RA) once judged regarding the blood money of a murdered man, and his wife came seeking her share. He said, "I do not know of anything for you; the blood money is for the agnates ('asaba) who pay the blood money on his behalf." Then Al-Dahhak ibn Sufyan Al-Kilabi stood and said, "The Messenger of Allah (ﷺ) wrote to me commanding me to give the wife of Ashyam Al-Dababi a share of her husband's blood money." So 'Umar gave her a share. Ibn Mas'ud said: "Every heir inherits from the blood money except the killer." Shariq said: "Debts are not paid from blood money, nor are wills executed." Rabi'ah said: "The ghurra (compensation) is for the mother of the fetus alone," which contradicts the consensus.
If you ask: "Upon whom is the slave and the blood money?" I say: Upon the killer. However, the slave is from his own wealth, while the blood money is borne by his 'aqila (male relatives). If he has no 'aqila, it is from the Public Treasury; if that is not possible, then from his own wealth.
"...unless they give [it as] charity"
Unless they give it to him as charity by forgiving him. This is like His saying: "Unless they forgo it" (Al-Baqarah: 237), and "But to remit it as charity is better for you" (Al-Baqarah: 280). The Prophet (ﷺ) said: "Every act of kindness is charity." Ubayy recited: "Unless they give it as charity." If you ask: "What does 'give as charity' attach to?" I say: It attaches to "upon him" or "delivered," as if it were said: "The blood money is obligatory upon him, or he delivers it, except when they give it to him as charity." Its place is nasb (accusative) as an adverb of time, with the omission of the time, like saying "I sit as long as Zayd is sitting." It is also permissible for it to be a hal (state) from "his family," meaning "except as charitable ones."
"...from a people who are at enmity with you"
From a people of disbelievers who are at war. This refers to a man who becomes Muslim among his disbelieving people while he is among them and has not separated from them. Upon his killer is the expiation if he kills him by mistake, and his 'aqila owes nothing to his family because they are warring disbelievers. It is said: A man would become Muslim, then his people—who are polytheists—would come, and the Muslim army would raid them and kill him by mistake because they think he is a disbeliever like them.
"...and if he is from a people..."
Disbelievers who have a covenant, like the polytheists who made a treaty with the Muslims, and the Dhimmi (protected) people of the Book. His ruling is the ruling of a Muslim among Muslims.
"And whoever does not find [a slave]..."
Meaning he does not possess one, nor the means to acquire one.
"...then a fast of two months consecutively, [as] a repentance from Allah"
An acceptance from Allah and a mercy from Him. "Allah accepts the repentance of whom He wills" means He ordained this as a repentance from Him, or your transition from the slave to the fast is a repentance from Him.
This verse contains a great threat, warning, and intimidation. Hence, it is narrated from Ibn Abbas that the repentance of one who kills a believer intentionally is not accepted. Sufyan said: "When the scholars were asked, they said: 'There is no repentance for him.'" This is interpreted as them following the path of God in being severe and strict; otherwise, every sin is erased by repentance. The erasure of polytheism is sufficient evidence for you.
In the Hadith: "The passing of the world is easier to Allah than the killing of a Muslim man." And: "If a man were killed in the East and another in the West were pleased with it, he would be a partner in his blood." And: "This human is the building of Allah; cursed is he who destroys His building." And: "Whoever helps in the killing of a believer with even half a word will come on the Day of Resurrection with 'Despairing of the mercy of Allah' written between his eyes."
It is astonishing that people read this verse, see what is in it, and hear these great Hadiths and the statement of Ibn Abbas regarding the prevention of repentance, yet their empty greed, their following of desires, and their vain hopes lead them to covet forgiveness for the killer of a believer without repentance. "Do they not then reflect on the Quran, or are there locks upon their hearts?" (Muhammad: 24). Then Allah mentioned repentance for accidental killing due to the negligence that might occur regarding the necessary caution. This is a cutting off of hopes—and what a cutting off! But there is no life in those you call.
If you ask: "Is there evidence in this for the eternity in Hell of those who do not repent among the major sinners?" I say: How clear the evidence is, as it encompasses His saying: "And whoever kills..."—any killer, whether Muslim or disbeliever, repentant or unrepentant, except that the repentant one is excluded by other evidence. Whoever claims the exclusion of the unrepentant Muslim must bring similar evidence.