Do đó, nếu A đã mua một chiếc xe từ B, người đã đặt chiếc xe trong một nhà để xe đó A có quyền truy cập miễn phí và được phép giao hàng, thực tế hay xây dựng, từ nơi đó bất cứ khi nào anh ta muốn , chiếc xe được xây dựng thuộc sở hữu của A và nếu ông H bán cho C mà không có được sở hữu vật lý, bán là hợp lệ. | 138 Understanding Islamic Finance from the vendor whenever he Hence if A has purchased a car from B who has placed the car in a garage where A has free access and A is allowed to take delivery real or constructive from that place whenever he wishes the car is in the constructive possession of A and if he sells it to C without acquiring physical possession the sale is valid. This implies that as the purchaser has taken the liability of the risk he is considered the owner of the commodity although the asset commodity is still in the godown of the seller or even in any other country or area. Hence if a Karachi-based bank contracts to purchase one hundred thousand bags of fertilizer from a factory in Lahore and the factory sets the bags aside and gives constructive possession to the bank the bank is considered the rightful owner of the fertilizer and is capable of selling it to any third party. So long as the bags are not sold the asset market or price risk will be that of the bank and not of the factory. However one can promise to sell something which is not yet owned or possessed. Similarly one can promise to buy any asset with given specifications. In the case of promise the actual sale will have to be executed after the commodity comes into the possession of the seller with proper offer and acceptance and unless the sale is formally executed the promise will have no legal consequences. Normally a promise creates just a moral obligation on the promisor to fulfil his promise but if the promisee has incurred any liability or expense as a result of the promise and the promisor backs out the latter should be held responsible for the actual loss to the promisee. Prices and the Profit Margin As a principle Islam is not inclined to fix prices or profit margins for traders and leaves them to be settled by the forces of demand and supply. The holy Prophet pbuh is reported to have allowed the competitive price mechanism to balance the demand and supply of .