Does the prayer of evil against the oppressor revert to the one who supplicated it, or is it not answered?

It is permissible to supplicate against the oppressor, and it is not permissible to supplicate against others except in specific cases, such as supplicating against disbelievers who harm Muslims when there is no hope for their guidance. The supplication of the oppressed is answered, and there is no veil between it and Allah. If a Muslim supplicates with something that does not involve sin or severing ties of kinship, then Allah answers his supplication or averts from him an equivalent evil.