What is the ruling of Islamic law regarding a dispute over a commercial shop leased under an old, indefinite-term contract, where the current tenant has not paid rent for 17 years and refuses to vacate the shop, knowing that he received the shop from a previous tenant who paid him for it, while the heirs have not received any amount?

The old rent law is Islamically invalid because it does not specify the duration, and one of the conditions for a lease contract is that the duration must be known. Any contract that lacks a specified duration must be annulled. Even if it is said that the contract is month-to-month, each party has the right to terminate the lease whenever they wish. Therefore, the tenant does not have the right to prevent the owner from benefiting from his property, unless they agree on a known duration for a known rent. As for past rent, it should be referred to the judiciary.