Abū Dharr reported Allah’s Messenger ﷺ as saying that Allah, the Exalted and Glorious, said: “My servants, I have made oppression unlawful for Me and unlawful for you; so do not commit oppression against one another.”
This hadīth forms part of a long Hadīth-e-Qudsi (a Tradition in which the Blessed Messenger said that Allah had said to him so and so) narrated by Abū Dharr. Here Allah, the Exalted and Glorious, through His Messenger ﷺ forbids believers to commit oppression against one another. To commit oppression against a fellow being is so heinous that Allah first made oppression unlawful for His Exalted Self and then prohibited His servants to commit it. This enhances the enormity of the act and seriousness of the commandment.
The verb zalama, from which the noun zulm is derived, generally means: he did wrong or acted wrongfully, injuriously or tyrannically. These translations are correct in their own way, but in the Qur’ān, the word al-zulm signifies the putting of a thing in a place not its own, or putting it in a wrong place, or misplacing it; it may also mean transgressing the proper limit.
Thus, in the light of these meanings of the word zulm, as used in the hadīth here, implies that Allah does no wrong; whatever He does is based on justice; even when He punishes His servants He does what is good for them. So far as oppression on the part of human beings is concerned, it means high-handedness against others.