Islamic law (Shari`ah) makes it permissible to utter harsh speech and to invoke Allah against those who have wronged one, trying to pray to Almighty Allah to help one regain one’s usurped right.
Dr. Ahmad Yusuf Sulaiman, professor of Islamic Shari`ah, Faculty of Dar Al-`Ulum, Cairo University, states: Almighty Allah says: (Allah loveth not the utterance of harsh speech save by one who hath been wronged. Allah is Ever Nearer, Knower) (An-Nisa’ 4:148). This means that Allah does not love those who utter harsh speech and invoke Him against other unless they have been wronged, in which case it is permissible.
However, scholars still differ on how to utter harsh speech against oppressors and what its permissible limit is. Some of them view that when someone wrongs another, the wronged one should not invoke Allah against the oppressor, but he should rather say, “Support me against him, Allah! Help me get my usurped right back, Allah! Prevent him from wronging me, Allah!” In this regard, Al-Qurtubi said, “This is defensive invocation against the oppressor, which is the least level of harsh speech.”
Some other scholars maintain that it is permissible for the oppressed to invoke Allah against the oppressor; yet if the former is patient and tolerant, it is better for him. On the other hand, some other scholars view that it is permissible for the oppressed to equally wrong the oppressor and publicly utter harsh speech against him.
According to the apparent meaning of the verse, it is permissible for the oppressed to equally wrong back the oppressor, but he must be moderate if the oppressor is a believer. If the oppressor is not a believer, it is permissible to invoke Allah against him as the Prophet (peace and blessings be upon him) did against some tribe when they killed some of his Companions whom he had sent to those tribes to teach them the Noble Qur’an.
Moreover, if the oppressor shamelessly and publicly declares his wrongdoing, it is permissible to invoke Allah against him publicly. To illustrate, Abu Dawud narrated that something was stolen from `A’ishah (may Allah be pleased with her), so she kept invoking Allah against the thief. Upon that, the Prophet (peace and blessings be upon him) said to her, “Do not make it lighter for him,” that is, do not make Allah lessen his punishment by your invocation against him. Moreover, the Prophet (peace and blessings be upon him) said, “The solvent’s procrastination of payment is a kind of oppression that gives people the chance to smear his reputation and injure his dignity.” The punishment of such a person is jailing.
Furthermore, it is stated in Imam Muslim’s Sahih that the Prophet (peace and blessings be upon him) said, “Delay (in the payment of debt) on the part of a rich man is injustice.” Thus, if someone is rich or solvent enough to settle his debts yet he elusively delays them, people have the chance to smear his reputation and injure his dignity. This means that it is permissible in this case to disgrace him by disclosing his oppression and injustice publicly. In other words, he will be known among people for his procrastination in giving rights back to their owners. Also, the imam or judge can subject him to disciplinary punishment that depends on the discretion of the imam.