عَنِ ابْنِ عُمَرَ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «الظُّلْمُ ظُلْمَاتٌ يَوْمَ الْقِيَامَةِ» . مُتَّفق عَلَيْهِ
It is narrated from Ibn Umar, may Allah be pleased with him, that the Prophet, peace and blessings be upon him, said: "Oppression will be the cause of many darknesses on the Day of Resurrection." Agreed upon.