What is the ruling on exchanging a commodity whose purchase is financed by the bank for another commodity in order to obtain a specific item whose invoice is not available to the bank, and is this considered usury (riba)? And what is the ruling on borrowing from a financing fund in which the borrower participates and the profit accrues to all participants, and is this considered usury (riba)?

If you wish to obtain cash that is not available through Murabaha contracts, you can resort to "Tawarruq," which involves buying a commodity from the bank on credit, and then selling it for cash to a party other than the bank. This type of transaction has been permitted by the majority of scholars, provided there is no usurious trick involved, such as appointing the bank as an agent to sell the commodity. As for lending with a stipulated increase, it is usury (riba) and is forbidden by the unanimous consensus of scholars.