Is treating the abuser in kind an injustice to people that necessitates the restoration of rights, or is repentance sufficient?

Responding to ill-treatment in kind is not considered injustice, if it is proportionate to the offense without excess. The wronged person has the right to seek retribution from their oppressor commensurate with the injustice they suffered. Texts from the Quran and Sunnah indicate the permissibility of seeking retribution, though patience and forgiveness are better. It is not permissible for someone who has been verbally abused to retaliate except with the same kind of abuse, unless it involves falsehood, slander, or insulting one's ancestors. The wronged person seeking retribution from their oppressor is permissible and not an act of injustice, but forgiving the oppressor is better. Therefore, if one is wronged by being struck or verbally abused, they may retaliate in kind, except for that which is forbidden as a right of Allah.