And because what is due is known in both quantity and quality, so it is not permissible to fall short in quality, just as it is not permissible in quantity. As for usury, it does not apply here because what is discharged is the right of [Allah Almighty], and there is no usury between the servant and his Master. Furthermore, equality in the legal standard is only considered in exchange contracts, whereas the purpose of Zakat is mutual assistance, enriching the poor, and expressing gratitude for the blessing of Allah Almighty, so usury does not enter into it. If it is said: If one pays two poor-quality animals instead of a fine one in livestock, or pays two poor-quality qafiz (measures) instead of one fine qafiz, it is not permissible, so why have you permitted that one may pay more than the obligated amount in clipped [coins] instead of perfect ones? We reply: That is permissible if there is [in what he paid] no defect other than the decrease in value. If [we concede that point], the difference between them is that the purpose of currency is value and nothing else; therefore, if the obligatory amount and the paid amount are equal in value and quantity, it is permissible. In other types of wealth, the intent is to benefit from the actual items themselves, so equality in those two aspects does not necessarily entail validity, as some of the intended purpose might be lost.

Section: Is it permissible to pay one of the two types of currency (gold or silver) instead of the other? There are two narrations regarding this, and the author explicitly mentioned both. The first is that it is not permissible, which is the choice of Abu Bakr, because it is not permissible to pay one type of the same genus for another if it is less in amount, so with a difference in genus, it is all the more so. The second is that it is permissible, which is more correct, if Allah wills, because the purpose of one is achieved by paying the other, so it suffices, just like types within the same genus. This is because the purpose of both of them is medium of exchange and using them to reach intended objectives, and they share this equally, so it resembles paying clipped coins instead of perfect ones. This is unlike other genera and types upon which Zakat is due, for each genus has a specific purpose that cannot be achieved by another genus, and the same applies to its types, so it does not...