Chapter 11 of this classical work by Imaam Ibn Al-Jawzi (d. 597H, rahimahullaah) is very interesting. This traditional scholar and Shaykh refutes Sufism, highlighting how it is wrong, evil and a path of misguidance and deviation. The section starts from page 270 and ends page 506, so over 230 pages in total, a lengthy and detailed critique based upon knowledge and insight, alhamdulillah. Well worth a read for those seeking to be illuminated.