And the second is that it is permissible, as Abū Hanīfah and al-Shāfiʿī held. Ahmad’s disapproval of exchanging goods sold by measure or weight for other goods sold by measure or weight may be understood as discouragement rather than prohibition. Alternatively, it may apply when taking possession is delayed. This latter interpretation is more consistent with Ahmad’s principles and explicit statements, and is what the scriptural evidence requires.

For when goods sold by measure are exchanged for goods sold by measure, or goods sold by weight for goods sold by weight, he requires that both countervalues be due immediately and that both parties take possession. If one category is exchanged for the other, two views are reported from him. This rests on the view that the effective cause of the prohibition concerning the six commodities is likeness: being of the same kind and sold by measure, or being of the same kind and sold by weight.

The scholars agree that exchanging gold for silver on a deferred basis is impermissible. Likewise, exchanging wheat, dates, barley, or salt for one another on a deferred basis is impermissible. Thus, whoever identifies the effective cause as likeness—whether in being sold by measure or weight, in being food, or in combining both characteristics—prohibits deferment whenever the two commodities share a single effective cause. All these positions are reported from Ahmad.

Likeness, meaning that the goods are of the same kind and sold by measure, or of the same kind and sold by weight, is the position most widely reported from him. It is also the school of Abū Hanīfah.

Being food is the criterion adopted by al-Shāfiʿī. Combining the two characteristics is the position of Ibn al-Musayyib and others, one of al-Shāfiʿī’s two positions, and the view preferred by Shaykh Abū Muhammad al-Maqdisī. Mālik’s position is close to this: his criterion is being a staple food or something used to prepare it.

Accordingly, when a debt arising from a salam contract, or any other debt, is settled with goods sold by measure, possession of those goods must be taken during the session in which the exchange is agreed. The same applies to goods sold by weight when they are exchanged