Jābir ibn ‘Abdullah (may Allah be pleased with him and his father) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "Beware of oppression, for oppression will be layers of darkness on the Day of Judgment; beware of stinginess, as stinginess ruined those before you. It incited them to shed their blood and regard the unlawful as lawful."
The Prophet (may Allah's peace and blessings be upon him) warned against oppression, which includes oppressing people, oppressing oneself, and committing oppression regarding the right of Allah Almighty, i.e., refraining from giving each one his due right. He stated that oppression will be layers of darkness on the Day of Judgment for those who commit it, given the hardships and horrors that will occur to them on that day. He also forbade stinginess, which refers to extreme miserliness and avarice; an example is showing negligence in fulfilling financial rights and an intense keenness to achieve worldly gains. This kind of oppression ruined those who preceded us from the previous nations as it drove them to kill each other and to permit what Allah has prohibited.