I heard Amir al-Mu’minin `Ali b. Abi Talib (as) say: The seekers of knowledge are of three types. You can distinguish them from each other by their characteristics and signs. (1) One group are those who learn for insincere argumentation. (2) One group are those who learn for stonewalling and deception. (3) One group are those who learn for understanding and for acting by it. As for those of insincere argumentation, they bring harm and doubt to groups of men. They gown themselves in reverence, but they are void of piety. May Allah knock their chests and cut their noses. As for those who learn for stonewalling and deception, they obstruct those like them, and they humble themselves for the rich. Thus, they consume those for their sweetness, and they destroy their religion. May Allah blind them from their sight and sever their affect on the legacy of the scholars. As for the group who learn for understanding and for acting by it, they are seen melancholy and grieving. They stand in prayer in the darkness of the night, and they bow in their evening robes. They work [in good deeds], and they are cautious and afraid of everyone except their trusted brethren. May Allah strengthen their foundations and grant them safety on the Day of Resurrection.