Is assignment valid when one party owes an unliquidated debt, such as the deferred price subject to an option?
General Chapter
Al-Mughni
Book of Assignment (Transfer of Debt)
Primary text
If the seller assigns the purchase price against the buyer during the option period, it is invalid according to established analogy. If the buyer assigns it to the seller, it is valid as it equates to fulfillment. If the seller assigned the price, and a defect is discovered, one view is that the assignment is not voided because the price was firm and the sale binding at the time of assignment, though the buyer gains the right to rescind. Another view suggests nullification because the defect existed at the time of assignment. If a non-firm debt assigned is later extinguished (e.g., divorce or rescission of sale) before fulfillment by the assigned party, one opinion is that the assignment is voided and the assignor reverts to the assigned party. The second opinion holds it is not voided because the right transferred permanently. If extinguishment happens after fulfillment, it is universally not voided, and the assignor reverts to the assignee.
Supporting text
If a party without a debt owing assigns to another who owes him a debt, this is not an assignment but a mandate (Wakala), subject to the rulings of mandate, as assignment requires the transfer of a right, which is absent here. If one who has a debt owing assigns to someone who owes him nothing, it is not an assignment according to Ahmad. The assigned party is not obligated to pay, nor is the assignee obligated to accept, as assignment is a form of exchange, which is absent here; it becomes a loan. If the assignee takes the money, he reverts to the assignor as it was a loan. If he grants remission without taking possession, the remission is invalid as it is remission to someone not owed the debt. If he takes possession and then gifts it, the assigned party reverts to the assignor for having discharged payment, requiring a new contract for repayment. Alternatively, he might not revert as he discharged nothing personally.