Thirty-Sixth Principle: Meeting the aggressor with a response equal to his aggression
The Qur’an lays down the following approach: it permits lawful retaliation against the one who assaults you, strictly in proportion to his assault; it forbids exceeding that limit and doing him injustice; and it urges forgiveness and benevolence instead.
Numerous verses spell this out, among them His words in Sūrat an-Naḥl: “If you retaliate, then retaliate with the like of that with which you were afflicted; but if you are patient, that is certainly better for those who are patient” (16:126). Likewise in Sūrat ash-Shūrā: “The requital of an evil act is an evil act like it; but whoever pardons and makes amends, his reward rests with Allah, for He does not love the wrongdoers” (42:40). In these two verses the three levels are mentioned.
Because fighting inside the Sacred Mosque is forbidden, He said in Sūrat al-Baqarah: “If they fight you, then kill them—such is the recompense of the disbelievers. But if they desist, then Allah is All-Forgiving, Most Merciful. Fight them until persecution ceases and religion belongs wholly to Allah; but if they desist, then there is to be no aggression except against the oppressors. The sacred month for the sacred month, and all sanctities are subject to equitable retaliation” (2:191-194). The phrase “all sanctities” covers everything Allah has declared inviolable and ordered us to respect.
Whoever violates any of these sanctities has, by that very act, allowed proportionate retaliation against himself—no more than what he committed. Allah also says: “Whoever transgresses against you, transgress against him in the same manner that he transgressed against you, and fear Allah” (al-Baqarah 2:194).
Further verses include: “O you who believe, retribution (qiṣāṣ) for the slain has been prescribed for you: the free for the free, the slave for the slave, and the female for the female” (al-Baqarah 2:178); “We ordained for them therein: a life for a life” (al-Māʾidah 5:45); “Whoever is killed unjustly—We have given his heir authority, but let him not exceed the limits in killing; indeed, he is aided” (al-Isrāʾ 17:33); and “Allah does not like the public utterance of evil speech, except by one who has been wronged. Allah is All-Hearing, All-Knowing” (an-Nisāʾ 4:148).
Verses conveying this meaning are many indeed. Allah knows best.