it is within his power, he returns it, because ownership of the usurped item did not cease to be his.

Section: If the price of the share was something measurable by volume or weight, and it perished before he took possession of it, the sale is void, and the preemption is void; because delivery has become impossible, so the execution of the contract is impossible, and thus preemption is not established, just as if he had rescinded the sale during the option period, unlike [the case of] rescission (iqala) and return due to a defect. If the preemptor had already taken the share, it is as if he had taken it in the preceding case; because the purchaser of the share has the right to dispose of it before he has been given possession of its price, so it is similar to if a third party had purchased it from him.

Section: If he purchased a share with a slave or a specified price, and it turns out to be rightfully owned by someone else (mustahaq), then the sale is void, and there is no preemption in it; because it [preemption] is only established in a contract that transfers ownership to the purchaser, which is the valid contract, whereas for the void one, its existence is like its non-existence. If the preemptor had already exercised preemption, he is obligated to return what he took to the seller, and this is not established except by evidence or an admission by the preemptor and the transacting parties. If the two transacting parties admit it, but the preemptor denies it, their statement is not accepted against him, and he has the right to take it by preemption, the slave is returned to its owner, and the seller seeks recourse from the purchaser for the value of the share. If the preemptor and the purchaser admit it, but not the seller, preemption is not established, and it becomes mandatory for the purchaser to return the value of the slave to its owner. The share remains with him, claiming that it belongs to the seller, while the seller denies it and sues him [the purchaser] for the obligation to return the slave, but the seller denies it [the sale], so he [the purchaser] purchases the share from him, and they absolve one another. If the preemptor and the seller admit it, but the purchaser denies it, it becomes mandatory for the seller to return the slave to its owner, preemption is not established, and the seller does not possess the right to demand anything from the purchaser; because the sale is valid in outward appearance, and he has already paid its price, which is his property in outward appearance. If the preemptor alone admits it, preemption is not established, and none of the consequences of voidness are established regarding the transacting parties. As for if he purchased the share with a price in the liability (dhimma), then he paid the price, and it turned out to be rightfully owned by someone else, then preemption is mandatory; because the sale is valid. If taking possession of the price from the purchaser is impossible due to his insolvency or otherwise, the seller has the right to rescind the sale, and the right of the preemptor is given precedence; because by taking it through [preemption], the purchaser obtains what he uses to pay the price, thus his insolvency is removed, and the combination of the two rights is achieved, so it is more appropriate.