Is selling a device that has potential harm, while informing the buyer of all the details and offering to take the device back for a refund, sinful, or is benefiting from the money impermissible?

If a person sells a defective device, and the buyer stipulates the option to return it if he cannot sell it, this is considered a conditional option with an unknown term.

- The majority of jurists hold that a conditional option is not valid unless it is for a known term; because an unknown term leads to ambiguity and dispute. - The Hanbalis, in one narration, hold that it is absolutely valid without a known term. - If the condition is invalid, there is a difference of opinion among scholars regarding whether the contract is void or فاسد (voidable/corrupt), or if the condition is void without the contract, or if the contract is valid with the condition modified, or if the contract is valid and the condition remains. - Those who deem the contract فاسد (voidable/corrupt) stipulate that it must be annulled, the device and the price returned, and a new contract concluded. - Those who deem the contract valid see no harm in retaining the price. - The contracting parties can agree on a known option period to rectify the contract and the condition.