“Do not kill any person whom Allah has forbidden to kill, except with right. We have granted the heir of him who has been wrongfully killed the authority to (claim retribution); so let him not exceed in slaying. He shall be helped.”
(Al-Qur’ān – 17:33)
God has declared human life to be sacrosanct, and thus not only slaying others, but killing oneself, i.e. suicide is also a heinous crime.
Later on, Islamic law declared taking life as legitimate in only five specific cases: retribution against one guilty of deliberate murder; fighting and killing those who wage armed resistance against the true faith; capital punishment for those engaged in any uprising against the Islamic system of government; capital punishment for those men and women convicted of unlawful sexual intercourse; capital punishment for those who committed apostasy. It is only in these five cases that human life forfeits its sanctity, and the taking of human life becomes lawful.
That ‘We have granted the heir of him who has been wrongfully killed the authority to demand qisas (retribution)’ means that the heir of someone who has been murdered is entitled to claim retribution for that crime, i.e. the murderer’s life be taken in retribution. This verse accounts for the principle of Islamic law which stipulates that in the case of homicide it is the heirs of the person slain rather than the state who are the plaintiffs. As a consequence, the heirs have the right to full retribution or gratuitously forgive the culprit or to altogether forego the right of retribution in lieu of blood-money.