The textual case has three cumulative features:
1. An amount equal to the debt was received.
2. The recipient spent those coins.
3. Only afterward did he discover their deficient quality.
This is not automatically identical to a dispute about still-identifiable coins that could be returned. Applying the disagreement requires the same factual sequence as the text.
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Why spending the coins matters
Kitab al-Rahn: Salam, Sarf, Third-party Custody and Fungible Collateral
The textual case has three cumulative features:
1. An amount equal to the debt was received.
2. The recipient spent those coins.
3. Only afterward did he discover their deficient quality.
This is not automatically identical to a dispute about still-identifiable coins that could be returned. Applying the disagreement requires the same factual sequence as the text.