Is the failure to take possession of the price at the contracting session considered an impediment to the validity of a Salam sale, in the event that the intermediary website transfers the money within a week, and is it a condition to inform the buyer of not owning the merchandise, and is it permissible for the buyer to return the commodity and reclaim his money in a Salam sale?

One of the conditions for a salam transaction is that the sold item must be described in terms of liability, not specifically designated. It is not a condition for the buyer to know that the seller does not own the goods. The intermediary website receiving the price without the amount entering the seller's guarantee does not fulfill the condition of possession at the contract مجلس (session). Allowing the buyer to return the goods and reclaim the price—even if there is no defect—is permissible if the seller agrees, and it is considered a form of annulment (iqālah).