Allah states that the believer is not allowed to kill his believing brother under any circumstances. In the Two Sahihs, it is recorded that Ibn Mas`ud said that the Messenger of Allah said,

«لَا يَحِلُّ دَمُ امْرِىءٍ مُسْلِمٍ يَشْهَدُ أَنْ لَا إِلهَ إِلَّا اللهُ، وَأَنِّي رَسُولُ اللهِ، إِلَّا بِإِحْدَى ثَلَاثٍ: النَّفْسُ بِالنَّفْسِ، وَالثَّيِّبُ الزَّانِي، وَالتَّارِكُ لِدِينِهِ الْمُفَارِقُ لِلْجَمَاعَة»

(The blood of a Muslim who testifies that there is no deity worthy of worship except Allah and that I am the Messenger of Allah, is sacred, except in three instances. (They are:) life for life, the married adulterer, and whoever reverts from the religion and abandons the Jama`ah (community of the faithful believers).) When one commits any of these three offenses, it is not up to ordinary citizens to kill him or her, because this is the responsibility of the Muslim Leader or his deputy. Allah said,

﴿إِلاَّ خَطَئاً﴾

(except by mistake). There is a difference of opinion concerning the reason behind revealing this part of the Ayah. Mujahid and others said that it was revealed about `Ayyash bin Abi Rabi`ah, Abu Jahl's half brother, from his mother's side, Asma' bint Makhrabah. `Ayyash killed a man called Al-Harith bin Yazid Al-`Amiri, out of revenge for torturing him and his brother because of their Islam. That man later embraced Islam and performed Hijrah, but `Ayyash did not know this fact. On the Day of the Makkan conquest, `Ayyash saw that man and thought that he was still a disbeliever, so he attacked and killed him. Later, Allah sent down this Ayah. `Abdur-Rahman bin Zayd bin Aslam said that this Ayah was revealed about Abu Ad-Darda' because he killed a man after he embraced the faith, just as Abu Ad-Darda' held the sword above him. When this matter was conveyed to the Messenger of Allah , Abu Ad-Darda' said, "He only said that to avert death.'' The Prophet said to him,

«هَلَّا شَقَقْتَ عَنْ قَلْبِه»

(Have you opened his heart) The basis for this story is in the Sahih, but it is not about Abu Ad-Darda'. Allah said,

﴿وَمَن قَتَلَ مُؤْمِناً خَطَئاً فَتَحْرِيرُ رَقَبَةٍ مُّؤْمِنَةٍ وَدِيَةٌ مُّسَلَّمَةٌ إِلَى أَهْلِهِ﴾

(and whosoever kills a believer by mistake, he must set free a believing slave and submit compensation (blood money) to the deceased's family) thus, ordaining two requirements for murder by mistake. The first requirement is the Kaffarah (fine) for the great sin that has been committed, even if it was a mistake. The Kaffarah is to free a Muslim slave, not a non-Muslim slave. Imam Ahmad recorded that a man from the Ansar said that he brought a slave and said, "O Messenger of Allah! I have to free a believing slave, so if you see that this slave is a believer, I will free her.'' The Messenger of Allah asked her,

«أَتَشْهَدِينَ أَنْ لَا إِلهَ إِلَّا اللهُ؟»

(Do you testify that there is no deity worthy of worship except Allah) She said, "Yes.'' He asked her,

«أَتَشْهَدِينَ أَنِّي رَسُولُ اللهِ؟»

(Do you testify that I am the Messenger of Allah) She said, "Yes.'' He asked,

«أَتُؤْمِنِينَ بِالْبَعْثِ بَعْدَ الْمَوْتِ؟»

(Do you believe in Resurrection after death) She said, "Yes.'' The Prophet said,

«أَعْتِقْهَا»

(Then free her.) This is an authentic chain of narration, and not knowing the name of the Ansari Companion does not lessen its authenticity. Allah's statement,

﴿وَدِيَةٌ مُّسَلَّمَةٌ إِلَى أَهْلِهِ﴾

(and submit compensation (blood money) to the deceased's family) is the second obligation which involves the killer and the family of the deceased, who will receive blood money as compensation for their loss. The compensation is only obligatory for the one who possesses one of five; as Imam Ahmad, and the Sunan compilers recorded from Ibn Mas`ud. He said; "Allah's Messenger determined that the Diyah (blood money) for unintentional murder is twenty camels which entered their fourth year, twenty camels which entered their fifth year, twenty camels which entered their second year, and twenty camels which entered their third year.'' This is the wording of An-Nasa'i. This Diyah is required from the elders of the killer's tribe, not from his own money. In the Two Sahihs, it is recorded that Abu Hurayrah said, "Two women from Hudhayl quarreled and one of them threw a stone at the other and killed her and her unborn fetus. They disputed before the Messenger of Allah and he decided that the Diyah of the fetus should be to free a male or a female slave. He also decided that the Diyah of the deceased is required from the elders of the killer's tribe.'' This Hadith indicates that in the case of what appears to be intentional murder, the Diyah is the same as that for killing by virtual mistake. The former type requires three types of Diyah, just like intentional murder, because it is somewhat similar to intentional murder. Al-Bukhari recorded in his Sahih that `Abdullah bin `Umar said, "The Messenger of Allah sent Khalid bin Al-Walid to Banu Jadhimah and he called them to Islam, but they did not know how to say, `We became Muslims.' They started saying, `Saba'na, Saba'na (we became Sabians). Khalid started killing them, and when this news was conveyed to the Messenger of Allah , he raised his hands and said,

«اللَّهُمَّ إِنِّي أَبْرَأُ إِلَيْكَ مِمَّا صَنَعَ خَالِد»

(O Allah! I declare my innocence before You of what Khalid did.) The Messenger sent `Ali to pay the Diyah of those who were killed and to compensate for the property that was destroyed, to the extent of replacing the dog's bowl. This Hadith indicates that the mistake of the Leader or his deputy (Khalid in this case) is paid from the Muslim Treasury. Allah said,

﴿إِلاَّ أَن يَصَّدَّقُواْ﴾

(unless they remit it), meaning, the Diyah must be delivered to the family of the deceased, unless they forfeit their right, in which case the Diyah does not become necessary. Allah's statement,

﴿فَإِن كَانَ مِن قَوْمٍ عَدُوٍّ لَّكُمْ وَهُوَ مْؤْمِنٌ فَتَحْرِيرُ رَقَبَةٍ مُّؤْمِنَةٍ﴾

(If the deceased belonged to a people at war with you and he was a believer, the freeing of a believing slave (is prescribed);) means, if the murdered person was a believer, yet his family were combatant disbelievers, then they will receive no Diyah. In this case, the murderer only has to free a believing slave. Allah's statement,

﴿وَإِن كَانَ مِن قَوْمٍ بَيْنَكُمْ وَبَيْنَهُمْ مِّيثَاقٌ﴾

(and if he belonged to a people with whom you have a treaty of mutual alliance,) meaning, if the family of the deceased were from Ahl Adh-Dhimmah or with whom there is a peace treaty, then they deserve his Diyah; full Diyah if the deceased was a believer, in which case the killer is required to free a believing slave also.

﴿فَمَن لَّمْ يَجِدْ فَصِيَامُ شَهْرَيْنِ مُتَتَابِعَيْنِ﴾

(And whoso finds this beyond his means, he must fast for two consecutive months) without breaking the fast (in the days of) the two months. If he breaks the fast without justification, i.e. illness, menstruation, post-natal bleeding, then he has to start all over again. Allah's statement,

﴿تَوْبَةً مِّنَ اللَّهِ وَكَانَ اللَّهُ عَلِيماً حَكِيماً﴾

(to seek repentance from Allah. And Allah is Ever All-Knowing, All-Wise.) means, this is how the one who kills by mistake can repent, he fasts two consecutive months if he does not find a slave to free.

﴿وَكَانَ اللَّهُ عَلِيماً حَكِيماً﴾

(And Allah is Ever All-Knowing, All-Wise), we mentioned the explanation of this before.