Sahih Al Bukhari – Book of Oppressions
Volumn 003, Book 043, Hadith Number 629.
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Narated By Abu Huraira Razi Allah Anhu: Allah’s Apostle Peace Be Upon Him said, “Whoever has oppressed another person concerning his reputation or anything else, he should beg him to forgive him before the Day of Resurrection when there will be no money (to compensate for wrong deeds), but if he has good deeds, those good deeds will be taken from him according to his oppression which he has done, and if he has no good deeds, the sins of the oppressed person will be loaded on him.”

DEFINITION OF OPPRESSION
a : unjust or cruel exercise of authority or power
b : something that oppresses especially in being an unjust or excessive exercise of power