Is it permissible to exchange an item containing usurious material (riba) with another item, where some of the exchange involves items of the same genus (riba-bearing items) and others involve items of a different genus, or where the non-genus item is added to one or both sides?
Chapter on Riba (Usury) and Exchange (Sarf)
Al-Mughni
Book of Sales
Primary text
The established position holds that such a transaction is impermissible. Ahmad explicitly stated this in numerous instances, and the early companions of the madhhab adopted this view. Ibn Abi Musa stated unanimously that selling a sheathed sword or belt adorned with its metal (the same genus as the adornment) is impermissible. This ruling is narrated from Salim ibn Abdullah, Al-Qasim ibn Muhammad, Shurayh, and Ibn Sirin, and it is the position held by Al-Shafi'i, Ishaq, and Abu Thawr. The primary evidence supporting this prohibition is the Hadith narrated by Fudalah ibn Ubayd, where the Prophet, peace be upon him, was presented with a necklace containing gold and beads, purchased for nine or seven Dinars. The Prophet commanded, 'No, until they are clearly separated.' The gold was then removed separately, and the Prophet commanded, 'Gold for gold, weight for weight.' Furthermore, when a contract involves two different kinds of exchange mediums, one medium must be divided against the other according to the value of the other medium in itself. If the values differ, the counter-exchange must differ. When the values are equal, the exact division becomes unknowable because valuation is conjecture, and uncertainty in equality is treated as non-existence in matters of usury, just as selling an unmeasured heap (sabra) for an unmeasured heap based on conjecture is impermissible.
Supporting text
There is a secondary narration from Ahmad suggesting permissibility under the condition that the singular item is greater in amount than the item it is combined with, or that each party has an item of a different genus involved. For instance, it is narrated that Ahmad permitted the sale of butter (zabad) for milk if the amount of pure butter exchanged was greater than the butter contained within the milk. Another reported view, held by Hammad ibn Abi Sulayman and Abu Hanifa, permits the transaction under these same conditions (if the singular item is greater or if both sides contain different genus items). Al-Hasan, Al-Sha'bi, and Al-Nakha'i permitted selling a sword adorned with silver for Dirhams, arguing that if a contract can be upheld as valid, it must be upheld as valid rather than void, by interpreting the different elements appropriately, similar to assuming purchased meat is properly slaughtered or that the seller rightfully owns the item.