What is the opinion of the scholars of the Ummah and the Four Schools of Thought regarding Sheikh Al-Harith Al-Muhasibi and his book "Al-Tawahhum" (Illusion), and do you recommend reading it?

Al-Harith al-Muhasibi was one of the great imams of asceticism, and many scholars, such as Ibn Shadadhan, al-Khatib al-Baghdadi, and al-Dhahabi, praised him and his books. However, some scholars, such as Abu Zur'ah al-Razi and Imam Ahmad, warned against his books due to their excessive scrutiny, their deviation from the path of the Salaf, and his delving into 'ilm al-kalam (speculative theology). His books may be read by those who possess a good measure of knowledge to distinguish between what is beneficial and what is harmful. As for beginners, they should stick to books of asceticism that are pure from impurities.