Imam al-Ghazali and Hadith Sciences
As for the Hadith question there is a short monograph by al-mahdaly (see below). In this book al-mahdaly points out that there is more to the hadiths that Imam Ghazali quotes than meets the eye. Also and most importantly is the sharah of ihya by al-Murtada al-zabidi (d. 1205/1791) ithaf al-sadah al-muttaqin bi sharh asrar Ihya’ ‘ulum al-din (Cairo: Matba’a al-Maymaniya, 1311 AH.) A manuscript of which is available at Princeton University Library that seems to be the author’s own working copy (muswada) as there is quite a bit of crossing out.
In the ithaf the author provides detailed takhrij (verification) of the hadith that al-Ghazali quotes in depth much more than al-hafiz al-`Iraqi (d. 806 /1404) does in his al-mughni ‘an haml al-‘asfar fil al-‘asfar fi takhriji mafi al-Ihya’ min al-akhbar (published in the Margins of the ihya’ and separately; Riyad: maktab Dar Tabriya, 1995 ed. Ashraf b. Abdelmaqsood sample). Al-zabidi mentions that al-hafiz al-iraqi intended to write three versions takharij of the hadith of the ihya’ only the shorter version was the only one that was completed. The longer version of the takhrij was only completed up to book 7 -Mysteries of Pilgrimage. Al-zabidi claimed to have one copy of this work in which he used in his ithaf (c.f. 1:p123, 312) where he mentions al-takhrij al-saghir and al-takhrij al-kabir (the smaller verification and the grand verification- respectively).
It would be of interest to note at this juncture that for a scholar like al-Ghazali who wrote works of jurisprudence (fiqh) and jurisprudential theory (isul al-fiqh) he was never criticized for his hadith usage. Which begs the question how can a scholar who seems to know his hadith material in one field go so wrong in another? The answer to seemingly puzzling turn of events lies in the fact that for matters of pertaining to asceticism (zuhd) a scholar is allowed to use hadith that is of weaker standing than in ones that are allowed to be used in jurisprudence and this opinion is well know in Hadith circles. Even ibn al-Jawzi (d. 597/1201) who criticized al-Ghazali for using such material turns around and uses similar material in his book sifat al-safwa (Hyderabad, 1355 A.H.) Therefore it would seem to the astute reader that al-Ghazali knows his hadith material well contrary to popular belief. He may not know the intricacies of hadith sciences but he knows the texts and which ones to use in which occasion. We can therefore safely say that he know hadith (diraya la riwya)!
Also there was a project to print the takhrij of both al-Iraqi and al-zabidi on the margins of the ihya but I have only seen one volume in print and the link is provided below. Finally there is an effort that some enterprising collators in which they published the takhrij of al-Iraqi as separate book under the rubric of Hadith studies along with that of al-zabidi and al-subki’s list with a seditious title such as exposing al-Ghazali’s lack of knowledge of Hadith.
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