What is the recourse for a buyer when they discover undisclosed deception (Tadlis) in the sold item?
Chapter on Selling the Musarrah (Animal with milk retained in udder)
Al-Mughni
Book of Sales
Primary text
If the buyer desires to keep the deceptively sold item (mudallis) and take compensation (Arsh), they are not entitled to Arsh. This is because the Prophet (peace be upon him) did not grant Arsh in the case of a deliberately retained milk animal (Musarat), but rather gave the buyer two options: either keep it or return it for a measure of dates (Sa'un min tamr). Furthermore, since the deception itself is not considered a defect, compensation is not warranted on that basis alone. If returning the item becomes impossible due to its destruction, the buyer must pay the price because returning an item for which no Arsh is specified has become impossible, similar to cases where the item has no defect.
Supporting text
If the item develops a defect while in the buyer's possession before knowledge of the deception, the buyer has the right to return it, take back the full price, and receive compensation for the defect incurred while it was with them. Alternatively, the buyer may keep the item and receive nothing further. If the buyer knowingly confirms the deception but then disposes of the item, the right to return it is voided, analogous to disposing of an item known to have a defect. Delaying the return without disposal subjects the transaction to the same ruling as delaying the return of a defective item.