Al-Fudhayl Ibn Iyaad rahimahullah said:
Any evil doer can think he is a good person, the ignorant can think of himself as a scholar, the greedy thinks of himself generous, the stupid thinks of himself as intelligent; life is short and hopes are unlimited, yet many are too dazzled with themselves to see a clear picture for advancement.
Adh-Dhahabi rahimahullah said:
I swear by Allah that Fudhayl is right. One is also unjust, yet believes he is the oppressed, eats unlawfully and thinks himself pious, a sinner and thinks himself honest, and seeks knowledge but hasn’t even learned to implement it, even to his family.