The third form of overreaching that confers the right of rescission is exploiting the unsuspecting party (ghabn al-mustarsil).

Imam Ibn al-Qayyim said, “In the hadith: ‘Exploiting the unsuspecting is a kind of usury.’ The mustarsil is someone who does not know the going price and is unable to haggle; he simply relies on the seller’s honesty because of his own guilelessness. If he is overcharged by an excessive margin, he is entitled to the option of cancellation.”

Such overreaching is unlawful because it deceives the buyer.

One prohibited practice that occurs in some Muslim markets is as follows: when a newcomer brings goods to sell, the regular merchants agree among themselves not to bid on them. They appoint one of their number to negotiate, and when no one raises the bid, the owner is forced to sell to him cheaply. The rest then share the purchase with that intermediary. This is blatant overreaching and injustice; once the owner learns of the scheme, he has the right to revoke the sale and reclaim his merchandise. Anyone who engages in this kind of deception must abandon it and repent, and whoever becomes aware of it must censure those involved and inform the authorities so they can be stopped.

Fourth: the option based on fraud (khiyār al-tadlīs). This right arises when the sale is tainted by tadlīs, namely presenting a defective item as though it were sound. The term is derived from dalsa, meaning darkness, because the seller, by his fraud