Nahj al-Balāgha

Hadith 2229
intellect
٤٠٩. وَقَالَ (عليه ‏السلام): الْقَلْبُ مُصْحَفُ الْبَصَرِ.
409. Amīr al-mu’minīn, peace be upon him, said: The heart is the book of the eye.
Source: al-Sharīf al-Raḍī