Surah 27. An-Naml, Ayah 4

The implication is that people who do not believe in life after death concentrate all their endeavours, as a rule, on material gains alone, and cannot think of anything worthwhile beyond "their own doings". See also note [7] on 2:7 , which explains why the "causing" of this spiritual blindness and confusion - in itself but a consequence of man’s own behaviour - is attributed to God.

Those who reject Allah and follow Evil have a good conceit of themselves. Their deeds are pleasing to no one else. As they have rejected Allah's guidance, they are allowed to hug their own self-conceit, and given further respite for repentance. But they follow their own whims and wander about in distraction, as they have no standards such as guide the godly.