By our expression “practical,” we mean whatever does not pertain to creed, such as prayer and almsgiving; thereby excluded are matters of belief—like affirming the oneness of Allah and knowing His names and attributes—for these are not called fiqh in technical usage.

By our phrase “along with their detailed proofs,” we intend the evidences of fiqh that are discussed together with their specific legal questions; this excludes usul al-fiqh, because research in that discipline concerns only the general evidences of fiqh.

Second, when the term is taken as the title of this particular discipline, it is defined as: the science that studies the general evidences of fiqh, the manner of deriving rulings from them, and the condition of the one who derives them.

By “general evidences” we mean the overarching rules, such as the principle that a command denotes obligation, a prohibition denotes forbiddance, and validity entails enforceability. Particular evidences are therefore excluded; they are cited in usul al-fiqh only to illustrate a given principle.

By “the manner of deriving” we mean learning how rulings are extracted from their evidences through the study of linguistic rulings and indications—general and specific, absolute and restricted, abrogating and abrogated, and so forth. Mastery of these matters enables one to draw the rulings latent in the evidences of fiqh.

By “the condition of the one who derives” we mean recognition of the status of that person, namely the mujtahid (independent jurist). He is called the “deriver” because he extracts the rulings himself from their evidences, having reached the level of ijtihad. Hence discussion of the mujtahid, the conditions of ijtihad, its ruling, and related issues belongs to usul al-fiqh.

The Benefit of Usul al-Fiqh:
Usul al-fiqh is a science of lofty standing, immense importance, and abundant