Abu Yusuf and Muhammad instead allow the creditor in this case to return the equivalent of the debased coins and demand sound dirhams. In their analysis, the agreed standard of the performance is legally relevant.
For example, 100 sound dirhams were owed; 100 debased ones were received and spent. Under their view, the creditor returns an equivalent of those debased coins and seeks the 100 sound dirhams originally due. This is replacement, not double recovery.
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The two disciples’ alternative ruling
Kitab al-Rahn: Salam, Sarf, Third-party Custody and Fungible Collateral
Abu Yusuf and Muhammad instead allow the creditor in this case to return the equivalent of the debased coins and demand sound dirhams. In their analysis, the agreed standard of the performance is legally relevant.
For example, 100 sound dirhams were owed; 100 debased ones were received and spent. Under their view, the creditor returns an equivalent of those debased coins and seeks the 100 sound dirhams originally due. This is replacement, not double recovery.