You therefore learn that the ruling in this particular precedent was not affirmed because of anything peculiar to it, but on account of a quality it shares with other cases.

Two benefits arise from assigning a ruling to a confined (‘qāṣirah’) cause:

As the jurists state, a ruling may at times be based on a transferable cause and at other times on a confined one. When the confined cause is expressly mentioned in the revealed text, all the jurists agree on its validity; their dispute concerns causes that are derived by inference. The majority permit this, and that is the sound position. It is the school of Mālik, al-Shāfiʿī, and Aḥmad ibn Ḥanbal according to the transmissions from him, for he consistently argues with confined causes; it is likewise the preference of Abū’l-Khaṭṭāb and other Hanbalīs.

Qāḍī Abū Yaʿlā and a group, however, followed the Ḥanafīs in disallowing confined causes, though this is a view held by their later adherents. The quarrel centered on whether the operative cause of ribā in wheat, silver, and similar commodities is transferable or confined. Nothing has been transmitted on this point from Abū Ḥanīfah himself or his two companions, and what accords with their intelligence and merit is that they would not reject it categorically, just as they do not reject it where the cause is textually specified.

Using a confined cause has two advantages:

1. It restricts the ruling to the very instance named in the text and blocks any extension by analogy, so that no one imagines the ruling applies beyond the text’s locus. Thus the prohibition of carrion is explained by a cause that excludes properly slaughtered meat; the prohibition of blood by a cause that excludes sweat, saliva, and the like; the restriction of hady and uḍḥiyah sacrifices to livestock by a cause that excludes other animals; and the imposition of the ḥadd for wine by a cause that keeps blood and carrion outside its scope. Such examples are numerous—indeed, some maintain that all