What is the ruling on a person guaranteeing someone to obtain a loan from an Islamic bank, knowing that the loan method involves the nominal purchase of goods and their immediate resale to receive their value with an increase in repayment, and what is the ruling on guaranteeing in the event of a Sharia doubt in this transaction?

The process involves the issue of selling a commodity before taking possession of it, and the issue of Tawarruq (monetization). If the purchased commodity is food, it is not permissible to sell it before taking possession, based on the Prophet’s (peace be upon him) saying: "Whoever buys food should not sell it until he has taken possession of it." Therefore, the aforementioned guarantee is not permissible. However, if the commodity is not food, scholars have differed regarding the ruling on selling it before taking possession. Some have prohibited it absolutely, while others have restricted the prohibition only to food. Accordingly, there is leeway in the guarantee in this case. As for the issue of Tawarruq, it has already been answered.