In the Holy Qur'an

He grants wisdom to whom He pleases, and whoever is granted wisdom, he indeed is given a great good and none but men of understanding mind. (2:229)

In the Traditions

The Prophet said, "The very basis of man is his intellect, and the man devoid of intellect has no religion"

Imam al Kadhim in his advice to Hisham, "O Hisham, nothing has been bestowed upon the servants better than the intellect. The sleep of a man of intellect is better than the night vigil of an ignorant man. Every single Prophet that Allah has sent down has been a man of intellect, whose intellect supersedes the labour of all diligent workers. The servant is not considered as having fulfilled an obligatory act from among the acts made incumbent by Allah until he understands it."