Riyád-us Sáliheen Vol. 1 Chapter 26, Page 214
Unlawfulness of Oppression & Restoring others rights.
Allah, the Exalted says:
"There will be no friend, nor an intercessor for the Zalimún [Polytheists and the Wrongdoers], who could be given heed to." [40:18]
"And for the Zalimún [Wrongdoers, Polytheists and Disbelievers in the Oneness of Allah] there is no helper." [22:71]
Hadith No. 203
Jábir bin 'Abdulláh [ra] reported: Messenger of Allah [saw] said, "Beware of injustice, for oppression will be darkness on the Day of Resurrection; and beware of stinginess because it doomed those who were before you. It incited them to shed blood and treat the unlawful as lawful." [Muslim]
Hadith No. 204
Abú Hurairah [ra] Reported: Messenger of Allah [saw] said, "On the Resurrection Day, the rights will be paid to those to whom they are due so much that a hornless sheep will be retaliated for by punishing the horned sheep which broke its horns." [Muslim]
Commentary: This Hadíth makes it abundantly clear that there will be utmost justice on the Day of Resurrection. So much that Alláh will redress even the grievance of the aggressed animals against the aggressors. Thus, this Hadíth serves a severe warning for people. When animals, who are devoid of sense, will not be forgiven, how would mankind be, which is gifted with senses? The latter will not be pardoned if they are guilty of having been unjust to anyone without adequately compensating them.