Al-Mustasfa min 'ilm al-usul. (On Legal theory of Muslim Jurisprudence) is Imam Ghazali's work on the subject of Usul Al Fiqh. It is considered as one of the four great works in the subject.
The other three being,
1. The mùtazalite 'Abd al-Jabar (d. 415) al-Qadi's al-'umad;
2. Abu al-Husain (d. 473) al-Basri's al-mùtamad(commentary on al-'umad);
3. Al-Imam al-Haramain abu al-Màali (d. 478) Juywani's al-Burhan
Ghazali's
approach to
usul al-fiqh
, as articulated in this last and greatest work of Law,
al-Mustafa
, is based on the premise that, in essence, this science is knowledge of how to extract
ahkam
(rules) from the
Shari'ah
sources. (As for the science of
fiqh
, it concerns itself particularly with the Shari'ah rules themselves which have been established in order to qualify the acts of the locus of obligation, man.)
Accordingly,
Ghazali
views it as imperative that any discourse on usul focus on three essential elements: the
; the
adilla
(sources); and the means by which rules are extracted from these sources, which ultimately includes examination of the qualifications of the extractor, namely, the
mujtahid
.