The Corrupt Heart

"The heart becomes corrupt in six ways: 1] Committing sins in the hope of repenting (later on in life), [2] Seeking knowledge and not applying it, [3] Practice without ikhlas [i.e. sincerity], [4] Eating the sustenance of Allah without thanking Him for it, [5] Not being pleased with Allah's decree an...d [6] Burying the dead without learning from them." 

[Hasan Al-Basri (may Allâh have mercy on him)]