What is the ruling on taking an amount of 450,0 Saudi Riyals from a foreign bank that holds deposits of deceased individuals who have no heirs, in exchange for a bank guarantee of 1,0,0 Saudi Riyals and financial coverage of 550,0 Saudi Riyals, provided that the contract does not obligate the payment of the remaining amount after the guarantee period expires?

A letter of guarantee is permissible in Sharia because it is a surety (kafala) or an agency (wakala). Therefore, it is permissible for the bank to request a mortgage in exchange for the letter of guarantee. However, what was mentioned in the question about paying 550,0 in exchange for taking an additional 450,0 is a corrupt contract and a forbidden usurious amount. The matter becomes even more prohibited if the funds are from the inheritance rights of the deceased, which were seized by an unlawful entity.