Al-Hasan said that knowledge is of two kinds:

knowledge in the heart, which is the beneficial type; and knowledge on the tongue, which is God’s allegation against a human being.” Darimi transmitted it.

وَعَن الْحسن قَالَ: «الْعِلْمُ عِلْمَانِ فَعِلْمٌ فِي الْقَلْبِ فَذَاكَ الْعلم النافع وَعلم على اللِّسَان فَذَاك حُجَّةُ اللَّهِ عَزَّ وَجَلَّ عَلَى ابْنِ آدَمَ» . رَوَاهُ الدَّارمِيّ