131. This means that human life, which has been declared inviolable by God, can only be destroyed for just cause. As for what is meant by 'just cause', we ought to remember that three cases are embodied in the Qur'an whereas two additional cases have been stated by the Prophet (peace be on him). The cases mentioned by the Qur'an are the following:
(1) That a man is convicted of deliberate homicide and thus the claim of retaliation is established against him.
(2) That someone resists the establishment of the true faith so that fighting against him might become necessary.
(3) That someone is guilty of spreading disorder in the Domain of Islam and strives to overthrow the Islamic order of government.
The two cases mentioned in the Hadith are:
(1) That a person commits illegitimate sexual intercourse even after marriage.
(2) That a Muslim is guilty of apostasy and rebellion against the Muslim body-politic.
Except for these five reasons, slaying a human being is not permissible, regardless of whether he is a believer, a protected non-Muslim (dhimmi) or an ordinary unbeliever.