ولهذا يتعين المال في الوديعة، والوكالة، والغصب
Thus the particular property is identified in deposit, agency, and usurpation.
A deposit concerns the very deposited item, agency may concern a specified item owned by the principal, and usurpation concerns the owner's same property. By contrast, a general debt may call for an amount and kind of property rather than the very coins initially mentioned.
Comparison: A ring held in deposit is not the same as a generic debt of 100 dirhams: the first centers on a specific object, while the second centers on meeting its defined amount and quality.