Ihya' 'Ulum al-Din ("The Revival of the Religious Sciences") is the work of Abu Hamid al-Ghazali, who died at Tus in 505 AH, in forty books arranged in four quarters: acts of worship, customs of daily life, things that destroy, and things that save 1 2. In his preface al-Ghazali says he wrote it "as a revival of the sciences of religion", having seen that knowledge of the path to the hereafter had become forgotten, and that he confined the book to the "knowledge of conduct" (mu'amala), leaving aside the "knowledge of unveiling" (mukashafa) 2 3. He put the Book of Knowledge first, then gave each quarter ten books 4 5 6. In the quarter of destructive things he gives each blameworthy trait its definition, cause, harms, signs and treatment 7 8. He says he cast the book in the mould of jurisprudence, itself in four quarters, "as a gentle way of drawing hearts in" 9 10.
Scholars differed over it: Hajji Khalifa reports from al-Nawawi that if the books of Islam were lost and the Ihya' remained it would suffice for what was lost, that Ibn al-Jawzi collected its errors in a book, and that the hadith master al-Iraqi traced its hadith 1. Ibn Taymiyya holds that it has much benefit, that it contains blameworthy matter from the philosophers and weak and fabricated hadith, and that the shaykhs' words in it that agree with the Qur'an and Sunna outweigh what is rejected, "and for this reason people's judgement on it differed and they disputed over it" 11 12.
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