From Jaabir ibn 'Abdullah (radiyallaahu 'anhu) who said that Allaah's Messenger (salallaahu 'alaihi wa'sallam) said:
Beware of committing oppression for on the Day of Resurrection oppression will be darkness, and beware of avarice for avarice destroyed those who came before you, it led them into shedding blood and into making lawful that which was forbidden for them.
Oppression is of two types: (i) A person oppressing his own soul and (ii) his oppressing others. Both of these have been forbidden by Allaah, the One free and far from all imperfections. So a person oppressing his own soul causes him to feel at home with his sins and to commit them, and causes him to abandon acts of obedience to Allaah.
The true Muslim is far removed from all of this and furthermore: