Are there specific supplications for seeking forgiveness for injustice, and is one who harms another with words or deeds while being in the wrong considered unjust?

If a person repents from injustice, his repentance requires conditions: If the sin is between the servant and his Lord, then the conditions of repentance are three: abandoning the sin, regretting it, and resolving not to return to it. However, if the sin relates to the right of another human being, a fourth condition is added to these three, which is restoring the right of the wronged person. If it was money, he must return it; if it was slander, he must enable the wronged person to inflict the prescribed punishment or seek his forgiveness; and if it was backbiting, he must seek his forgiveness. If it is impossible to reach him or if he fears further harm, he should pray for him frequently in his absence. There is no specific supplication for the penitent, but among the reported supplications is: "O Allah, forgive my sin, my ignorance, and my extravagance in my affairs..."

As for a wronged person criticizing the oppressor, it is permissible under two conditions: that he does not exceed what was done to him, and that he does not fear provoking a greater tribulation. If he refrains from doing so, it is better for him. It is permissible for the wronged person to openly supplicate against his oppressor and mention his evil deeds. However, it is not permissible for anyone other than the wronged person to harm others, unless he is in a position of authority to deter the oppressor or for the purpose of helping the oppressed by preventing injustice.