Al Fudhail Ibn Iyaad [rahimahuAllah] 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.”

Abu Dhahabi [rahimahuAllah] said:

“I swear by Allah that Fudhail 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 even to his family.”

(Sifat As Sawfah 8/440)