Assalamualaikum wa rahmatulla.
Hadhrat Sufyaan Thauri (R.A) says that ten people are regarded as oppressors viz.
1. The person who prays for himself, but forget his parents and other Mu'mineen.
2. The person who does not recite at least a hundred verses of the Qur'aan daily.
3. The person who leaves the Masjid without performing at least two rakaahs of salaah.
4. The person who passes a graveyard without greeting the deceased or praying for them.
5. The person who enters a city on a Friday and leaves without performing the Jumu'ah salaah.
6. That man or woman in whose vicinity a learned person comes and none acquires any religious knowledge from him.
7. Those two people who love each other for the pleasure of Allah but are unaware of each others names.
8. That person who is invited by another but does not accept his invitation (when acceptance does not contradict the shari'ah).
9. That youngster that has no commitments yet does not acquire any religious knowledge or manners.
10.That person who has eaten to his fill while his neighbour goes hungry.
Source:Tambihul Ghafileen