A form of prohibited sale (ba’i batil) in which a person or group of persons connive with a seller to bid up the price of a commodity offered for sale through an auction (mazad), not meaning to purchase but only to entice an unsuspecting bidder to offer higher prices, and eventually have him stuck with the object of sale. The ensnared buyer will have to pay an artificially determined price (a much higher price than fair or normal price). Ba’i al-tanajush is an Arabic term that translates as a sale through a fraudulent auction or sale involving a manipulative overpricing. This sale is based on collusion (tawatu’) between a seller and a fake (ghost) bidder.

Tanajush is derived from najsh which literally means concealment, rousing and chasing the game for the purpose of entrapping it.

Ba’i al-tanajush (بيع التناجش) is also known as ba’i al-najsh.