Imaam Ibn Hibbaan said:
And the intellectual; his own deficiencies are not hidden to him, because the one whose deficiencies are hidden to him will not see the good qualities of others.
And from the worst of punishments a person can suffer is that his own deficiencies are hidden to himself, because the one who doesn’t know his deficiencies cannot get rid of them….and the one who does not know the good traits cannot reach them….
and how beneficial is experience for the inexperienced .”
From the book: Rawdhatul Uqalaa wa Nuzhatul Fudhalaa [The Meadow of the Intellectual and the Vacation of the Virtous] of al-Imaam Ibn Hibbaan al-Bustee , Chapter: Characteristics of the Intelligent