Without doubt a supplication made by the oppressed against an oppressor reaches Allaah without any barriers. This is stipulated in the hadeeth. It is narrated in the hadeeth of Mu’aath ibn Jabal when the Prophet sent him to Yaman, he concluded his advice to him saying,
“Beware of the supplication of the oppressed, because indeed there is no barrier between it reaching Allaah.” (Bukhaary 1496)
There is also no doubt that supplicating against another person is not something Allaah likes. This is the case of making
(ٱلۡجَهۡرَ بِٱلسُّوٓءِ مِنَ ٱلۡقَوۡلِ إِلَّا مَن ظُلِمَۚ)
“… public mention of evil except by one who has been wronged.” (Al-Nisaa’ 148)
Hence, the oppressed has the right to make supplication against his oppressor in proportion to the oppression and no more.
(لَّا يُحِبُّ ٱللَّهُ ٱلۡجَهۡرَ بِٱلسُّوٓءِ مِنَ ٱلۡقَوۡلِ إِلَّا مَن ظُلِمَۚ)
“Allaah does not like the public mention of evil except by one who has been wronged.”
(Al-Nisaa’ 148)
However, if a person were not to supplicate hoping that Allaah will reward him, he can hope to receive the Reward for that from Allaah, Most Exalted and High. The meaning of ‘Forgiveness within one’s ability’ is that a person who has the right either:
a) has the ability to retake his right but decides to relinquish it. This is called complete forgiveness, or
b) if he cannot do so and his right is close to being lost, if he forgives at this point, this type of forgiving is lesser in rank than the aforementioned. However, his pardoning has set the person who has wronged him free of responsibility even if he cannot retrieve his right. This is included in the general Qur’aanic precept,
(وَأَن تَعۡفُوٓاْ أَقۡرَبُ لِلتَّقۡوَىٰۚ)
“… and to forego is nearer to righteousness.” (Al-Baqarah 237)