If a man who is in debt sells a slave to another person and, by way of ḥawāla (assignment of debt), directs his creditor to collect the sale-price from the purchaser, and the creditor accepts, then the later repossession of that slave from the purchaser does not invalidate the ḥawāla. The assignment stands exactly as it was; the purchaser must still pay, but he is entitled to recover the price of the slave that has been taken from him from the seller.

The same ruling holds if the original sale itself proves void: suppose a creditor of the seller accepts an assignment of the price, the transaction is then unwound, and the sale is rescinded. In that event the purchaser must satisfy the assignee and then seek reimbursement from the seller.

Likewise, when a man sells a commodity, transfers its price to a creditor by referring him to the buyer, and the buyer subsequently discovers a defect and returns the item, the buyer remains liable to pay the assignee and then recoups the price from the seller. If the commodity has perished so that it can no longer be returned, the same procedure applies: the buyer pays the assignee and then looks to the seller for reimbursement.

The principle extends to leases and the sale of fruit. If someone rents a house for cash, or buys a specified share of fruit after it has ripened, and the owner assigns the rent or the price to a creditor, the subsequent destruction of the fruit does not annul the ḥawāla. The party upon whom the debt has been assigned must pay what is demanded of him, after which he may recover that amount from the owner of the house or the fruit for what the assignee has taken from him.

Anyone who purchases a commodity on deferred payment may not assign its price in discharge of a debt owed to him, whether that debt is already due or still deferred; and the same prohibition applies to one who rents a house on deferred rent. Doing so would be an exchange of one debt for another (dīn bi-dīn). Once an instalment of the rent has fallen due, however, he may assign that matured portion against any debt, whether due or not.

A person who buys for cash a slave-girl belonging to the category of jawārī al-muwādaʿa (female slaves engaged in a staged manumission contract) may likewise not assign her price against any debt, whether due or deferred, because that would amount to dīn bi-dīn. The same rule, according to Ibn al-Qāsim, applies to fruit still hanging on the palms when it is purchased on credit.

Ashhab, however, maintained that such an assignment is permissible so long as the buyer has taken possession of the slave-girl and has likewise taken possession—by the legally recognised means—of the fruit while it is still on the trees.