And it is stated in part 30, Surah al-Burooj, verse 10:

اِنَّ الَّذِیْنَ فَتَنُوا الْمُؤْمِنِیْنَ وَ الْمُؤْمِنٰتِ ثُمَّ لَمْ یَتُوْبُوْا فَلَهُمْ عَذَابُ جَهَنَّمَ وَ لَهُمْ عَذَابُ الْحَرِیْقِؕ(۱۰)

Indeed those who tortured the Muslim men and Muslim women (by burning them), and then did not repent, for them is the punishment of Hell, and for them is the punishment of Fire.

[Kanz-ul-Iman (translation of Quran)] (Part 30, Surah Al-Burooj, Verse 10)

Violating rights is also oppression

Dear Islamic brothers! We have learnt that Allah Almighty has promised the punishment of the fire to those who do not uphold the rights of Muslims, those who oppress them and hurt them for no reason. Thus, we should remain very cautious and never scare, threaten or violate their rights without any reason.

Being unfair with a person, humiliating them in a large gathering, dishonouring them, swearing at them, hitting them and doing every such action that violates the right of another person is also oppression in reality. 

Definition of oppression

While stating the definition of oppression, Sayyid Shareef Jurjaani رَحْمَةُ الـلّٰـهِ عَلَيْه states the following: ‘Putting a thing in other than its place is oppression.’ (Al-Ta’reefat-lil-Jurjaani, p. 102) Whereas in Shari’ah, oppression refers to violating another’s right, spending on a wrong occasion and to punish someone without a reason. (Mirat-ul-Manajih, vol. 6, p. 669)

Remember! The consequence of oppression is very terrifying and frightening; the oppressor will definitely be subjected to punishment in the Hereafter, but sometimes, such a person is afflicted with severe circumstances in this world also.