–namely, that their right hands and left feet are severed on opposite sides. And if the offence is lighter still, they are banished from the land: either by life-long imprisonment, as some scholars have held, or by expulsion from the towns, as others have said. Yet if their harm cannot be restrained through banishment, they are to remain incarcerated until death.
In sum, whoever kills a person because that person is spreading corruption in the land is free of blame; indeed, killing someone who actively sows corruption on earth is an obligation. Retaliatory killing—one life for another—is permissible, except in the opinion of Imām Mālik (may Allah have mercy on him) and Shaykh al-Islām Ibn Taymiyyah, for in their view treacherous murder (ghīlah) requires mandatory retribution. That is, if someone takes another unawares and kills him, the murderer must be executed even if the victim’s heirs pardon him, because ghīlah is sheer evil and corruption that cannot be eliminated otherwise.
For example, if a man comes upon someone while he is sleeping and kills him, such a killer must be put to death in every case, even should the slain man’s heirs say, “We forgive him and seek nothing.” This is the position of Imām Mālik and Shaykh al-Islām Ibn Taymiyyah, and it is the correct view: when a person is killed by treachery, the killer must himself be killed, and the heirs have no discretion in the matter.
To conclude, Allah makes clear in this verse that killing a single soul—without it having taken a life or spread corruption in the land—is like killing all humankind, whereas saving a single life is like saving all humankind. This highlights the gravity of murder. Were someone to try to tally how many of Adam’s descendants have been slain unlawfully, he would find it impossible. Yet for every soul that is killed, the first son of Adam who murdered his brother bears a share of responsibility; upon him rests a portion of their sin.
That son of Adam killed his brother out of envy. When Adam’s first two children came into the world, they each offered a sacrifice seeking closeness to Allah, and Allah accepted from one of them