The first is the type of debt: for example, if he transfers one hundred sāʿs of wheat owed by him to someone who owes him one hundred sāʿs of wheat. But if he transfers him for one hundred sāʿs of wheat to one hundred sāʿs of barley, the transfer is invalid because the two types differ. This is not a transfer; rather, it is in reality a sale.

Likewise, if he transfers him for ten dinars to ten dirhams, this is invalid because the two types differ.

The second is the description: both debts must be of good quality, poor quality, or medium quality. The apparent meaning of the author’s words is that it is not valid to transfer a good-quality debt to a poor-quality debt, nor a poor-quality debt to a good-quality debt. But this is open to question, for there is nothing prohibited in that. If he transfers a good-quality debt to a poor-quality one, and the transferee accepts the poor-quality debt in place of the good-quality one, what prevents this? So long as the type and amount are the same, it involves neither usury nor uncertainty.

Thus, the one whose good-quality debt has been transferred to a poor-quality debt may say: “I prefer to take the poor-quality debt rather than have my entitlement remain owed by this poor or dilatory man.”

The reverse is likewise valid: if he transfers one hundred sāʿs of poor-quality grain to one hundred sāʿs of good-quality grain, there is nothing wrong with this, because the transferor has made the transfer willingly—just as if he had repaid a poor-quality debt with goods of good quality.

The correct view, then, is that when the description concerns poor or good quality, there is no harm in a difference between them.

The third is the due date. This applies when both debts are deferred: the two debts must have the same term. Thus, he may not transfer a debt due after one month