from the hirer into the transport the owner owes and the deferred additional payment. This involves replacing one debt with another if the additional payment consists of goods. If it consists of dinars, it involves exchanging goods and gold for gold on a deferred basis; if it consists of dirhams, it involves deferred currency exchange. If the additional payment consists of dinars or goods delivered immediately, this is permissible. If it consists of dirhams paid immediately while the hire charge is in dinars, this is impermissible according to Ibn al-Qāsim’s position, unless the amount is less than the exchange value of one dinar.
It has also been said that this is permissible even if the amount exceeds the exchange value of one dinar. This accords with the position of those who permit combining a sale with currency exchange and regard the discharge of obligations as different from their creation. Another opinion holds that this is impermissible even if the amount is less than the exchange value of one dinar. This accords with the position that discharging obligations is equivalent to creating them, which is the view of Ashhab and Ibn Nāfiʿ. According to their position, therefore, the transaction involves deferred currency exchange.
Al-Fadl held that, according to their position, it does not involve deferred currency exchange unless the contracted transport is deferred and not yet due. In my view, however, it makes no difference in guaranteed transport whether performance is due or not, since even when it is due, the hirer can receive it only gradually. Ibn Lubāba held that mutual rescission of a contract for guaranteed transport before payment is altogether impermissible, likening it to mutual rescission of a sale of absent goods before payment. His view follows by analogy from the position that discharging obligations is equivalent to creating them.
Section
If the hirer asks the owner to release him in return for an additional payment after paying the hire charge, whether before or after the owner has gone away with the payment, and the additional payment is gold, this is permissible only if it is deducted by way of set-off from the hire charge already paid, as explicitly stated in al-Mudawwana. If it consists of dirhams, the three opinions mentioned earlier apply: permissibility, prohibition, and distinguishing between an amount below the exchange value of one dinar and an amount above it.
If the additional payment consists of goods, they may be delivered either immediately or later, because the hirer has sold the transport to which he is entitled, together with the goods he gives immediately or later, in exchange for the hire charge he recovers. This is permissible. This, then, explains the rulings on the twelve cases in which the hirer seeks release in return for an additional payment.