A situation that arises when a sale is concluded over a previous sale. More specifically, it is the case when a third party attempts to sell something to (or buy something from) someone who is already in the process of concluding a transaction with someone else. In this sense, the third party is considered an intruder/interferer whether his intention is actual or manipulative trading. The intruder/interferer usually quotes a lower rate or informs a party of existing or potential defects in the underlying goods. Shari’a outspokenly forbids interfering in a closed deal (or an almost closed deal) by offering better terms to either party. The restriction takes effect after the trade is closed. A trade under shari’a is considered consummated when an offer to buy or sell the goods is accepted in any means (including verbally) by a party at the contract session (majlis al-aqd). Both parties to a business transaction have the right to rescind it so long as they have not parted ways. Some types of sales (buyu’) may be embedded with an option (khiyar) to annul the contract within a specific period of time.

Bay’ ala al-bay’ is an Arabic term (بيع على البيع) that translates as bidding on a finished deal (bidding on a concluded deal).