taunting, or doing so in his absence, which is backbiting.
It is not permissible to transgress against him by reviling him more than he reviled the other person (1), or more severely than he did. The Prophet (peace and blessings be upon him) said: “Whatever the two of them say is held against the one who began it, so long as the wronged party does not transgress.” (2) It is therefore understood that one who requites in kind incurs no sin, provided he [does not] transgress.
As for speech that is forbidden because it violates Allah’s right, such that it remains unlawful even if it causes the person no harm—such as falsely accusing him of fornication or falsely branding him an unbeliever or a sinner—it may not be requited in kind. The offender is, however, subject to discretionary punishment, just as with bodily injuries for which no retaliation is prescribed. Scholars have differed, with two views, as to whether such a matter may be settled in exchange for monetary compensation.
An analogous case is where someone kills another in a mutilating manner—for example, by burning him or cutting off his hands and feet. Should he be treated as he treated his victim, or may retaliatory execution be carried out only by the sword? Jurists have two well-known positions. The position more consonant with the Quran, the sunnah, and justice is that he should be treated as he treated his victim, unless the act is itself forbidden, such as forcing him to drink wine, subjecting him to sodomy, or the like (3).