If, however, the buyer alleges the defect and the seller denies it, this is not permissible, even if the buyer brings gold equal to the compensation due for the defect and exchanges it with him weight for weight. This is because he has agreed to this exchange only in return for the seller sparing him the burden and trouble of proving the defect, or of taking an oath. For if the seller declined to swear, the oath would fall to the buyer. Thus, his agreement to the exchange is given in return for being relieved of the oath, introducing inequality between the two amounts of gold exchanged.
According to Ibn al-Qāsim’s school, however, settlement in gold should be permissible if the buyer brings the amount of compensation due for the defect and exchanges it with the seller weight for weight, even if the seller denies the defect. For if the buyer declines the oath while advancing a false claim, he may not take anything from the seller, whether little or much. If his claim is rightful, however, he may make a weight-for-weight exchange for the amount he knows to be due as a reduction for the defect. What is unquestionably permissible is for the seller to reduce the price owed by whatever amount they agree upon, whether little or much.
Section
If the price is payable at a future date, the seller may settle with the buyer for goods or food delivered immediately, but not for goods deliverable at a future date, since that would involve exchanging one debt for another deferred debt. Nor may he settle for dirhams, whether payable immediately or at a future date. As for dinars, it is stated in al-Mudawwana that this is not permissible. One interpretation is that this refers to cases where the dinars agreed upon in settlement are less than the compensation due for the defect.
If they equal or exceed that compensation, however, the settlement is permissible, since the seller cannot be suspected of giving gold now in order to receive an equal or smaller amount when the payment falls due. This is the interpretation of Ibn Abī Zayd and Ahmad ibn Khālid.
Another interpretation is that this is impermissible in all cases where the seller denies the defect, even if the dinars equal or exceed the compensation due for it. This is because the seller has agreed to pay his dinars now in exchange for an equal or smaller amount payable at a future date only in return for the buyer sparing him a dispute over the compensation due for the defect. It thus becomes a loan yielding a benefit, as well as an exchange of dinars for dinars with deferred payment.