What is the ruling on giving a loan of 5 dollars on condition that 1 dollar be added to it as a fee upon repayment?

Transferring mobile credit to another person has two scenarios:

The first: As a sale, and this is permissible with no objection. It is permissible to sell it for more than its cost, as it falls under the sale of usufructs.

The second: As a loan, and this is also permissible. However, it is not permissible to stipulate the return of an amount greater than the transferred credit, because every loan that draws a benefit is usury (riba). Rather, one should return the equivalent of the credit borrowed. It is permissible to agree at the time of repayment to pay cash equivalent to its value on the day of repayment in exchange for the credit.

The difference between a sale and a loan is determined by the intention of the transacting parties. It is permissible to sell the credit for more than its value, whereas in a loan, one must return its equivalent.