not attained by paying what is not mandatory in terms of wisdom, whereas it is attained by [paying] the mandatory amount. Since the purpose is achieved here, its validity is required, as there is no benefit [in restricting] validity to a specific type when another is equal to it in wisdom, and when doing so is gentler and more beneficial for both the giver and the receiver, and prevents harm from both. For if it were mandatory to pay Zakat on dinars using dinars, it would be difficult for someone owning less than forty dinars to pay a fraction of a dinar, and he would need to fragment it, and share a dinar of his wealth with the poor person, or have one of them sell his share, [which would harm both the owner and the poor person]. But if it is permissible to pay dirhams instead, he pays the poor person an amount of dirhams equivalent to the obligation, which is easy for him, and the poor person benefits without any burden or harm. Furthermore, if he pays the poor person a piece of gold in a place where it is not used in transactions, or a piece of dirham in a place where it is not used in transactions, he will not be able to fulfill his needs with it. If he wants to sell it for the [type of currency] that is used, he will need the burden of selling, and he may not be able to do so, rendering it useless to him. Even if it is possible to sell it, he incurs the burden of selling, and it is likely that the substitute will be worth less than its value; thus he is caught between two harms. In permitting the payment of one type for another, there is pure benefit, the avoidance of this harm, and the realization of the wisdom of Zakat in its completeness and perfection, so there is no [need nor] reason to prohibit it. If one imagines a benefit that is lost by doing so, it is trivial and overwhelmed by the manifest benefit obtained and the harm and hardship prevented on both sides, so it is not considered. And Allah knows best. Based on this, substitution is not permissible in a situation where harm befalls the poor person, such as paying him something that is not spent in place of what is spent, because if it is not permissible to pay one type for another when there is harm, then it is all the more prohibited when there is even less.