Dhammapada 5.4.63

5.4.63

‘‘Yo bālo maññati bālyaṃ, paṇḍito vāpi tena so;
Bālo ca paṇḍitamānī, sa ve ‘bālo’ti vuccatī’’ti.

63. The fool who thinks he is a fool is for that very reason a wise man;
But the fool who thinks he is a wise man is rightly called a fool.