Hamza Yusuf

Afflictions that assail and control people--such as miserliness, envy, treachery, malice, and arrogance--are examined in a study that discusses the causes and cures of these diseases and reveals how Islamic spirituality deals with spiritual and psychological problems. Original.

Signs, Symptoms, and Cures of the Spiritual Diseases of the Heart : Translation and Commentary of Imam Mawlud's Matharat Al-Qulub

Purification of the Heart

Safiya 

I found the concise chapters liberating, because this means that you can open it an any time pick a "disease" and reflect on it.
I may perhaps prefer reading about it in Arabic rather than English, but the author made sure to keep his translation literal and include Arabic words as well. 
Ramadan 1442

Purification of the Heart Signs, Symptoms, and Cures of the Spiritual Diseases of the Heart : Translation and Commentary of Imam Mawlud's Matharat Al-Qulub