" Purifying the heart is a process. First, one must understand the necessity of having courtesy with God and the importance of fulfilling its requirements, as noted above. Second, one must be aware of the diseases of the heart—aware of their existence, their ailments, and the deleterious complications and troubles that ensue from them, and recognize that these diseases prevent one from attaining this courtesy. "

― Hamza Yusuf , Purification of the Heart: Signs, Symptoms and Cures of the Spiritual Diseases of the Heart