Oppression, a hadith qudsi
يَا عِبَادِي إِنِّي حَرَّمْتُ الظُّلْمَ عَلَى نَفْسِي وَجَعَلْتُهُ بَيْنَكُمْ مُحَرَّمًا، فَلَا تَظَالَمُوا
Ya 'ibadi, inni harramtu-z-zulma 'ala nafsi wa ja'altuhu baynakum muharraman, fa-la tazalamu.
"O My servants, I have forbidden injustice for Myself and I have made it forbidden between you, so do not wrong one another."
Narrated by Abu Dharr (hadith qudsi). Sahih Muslim 2577 · Nawawi's Forty · #24
A short reflection
Allah forbade wronging on Himself, voluntarily. How much more is it forbidden for us between each other.