He was asked:

About copper coins: exchanging them for one another in unequal amounts; exchanging them for silver dirhams without both parties taking immediate possession; and a person handing over a dirham and receiving copper coins for part of it and a piece of silver for the remainder.

He replied:

If someone hands over a dirham and says, “Give me silver for half of it and copper coins for the other half,” or similarly says, “Give me the equivalent weight of these heavy dirhams in half-dirhams or light dirhams,” this is permissible, whether the coins are debased or pure. Some jurists disapprove of this and classify it under the “mudd of ajwa dates” case, because he has exchanged silver and copper for silver and copper.

The underlying issue in the “mudd of ajwa dates” case is exchanging a commodity subject to the rules of riba for another of the same kind, with something of a different kind included on both sides or on one side. Scholars hold three views on this:

The first is prohibition without qualification. This is the position of al-Shāfi'ī and one opinion reported from Ahmad.

The second is permissibility without qualification, as held by Abū Hanīfa. This is also cited as an opinion reported from Ahmad.