Does Islamic Sharia permit long-term lease contracts (50-90 years), and is it permissible for the ولي الأمر (ruler/guardian) to restrict what is permissible by making them of indefinite duration by force of law, while fixing the rental value for many years?

The jurists have agreed on the condition of specifying the duration of a lease (ijarah) but have differed on its maximum duration. The majority of them hold that there is no maximum limit as long as the leased asset remains fit for leasing, citing as evidence the Almighty’s saying in the story of Shu'aib: {on condition that you hire me for eight years; but if you complete ten, it will be [a favor] from you}. Others have held different opinions, such as stipulating that it should not exceed one year or thirty years.

The ruler (wali al-amr) may restrict permissible matters for the benefit of the nation, but he is not allowed to validate contracts that are religiously void, such as lease contracts of unspecified duration. The principle in leasing is the stability of the rent throughout the contract period, but it is permissible to agree to link the rent to a precise index for periods following the first period, provided that an upper and lower limit for the index is specified, to ensure the absence of uncertainty and dispute.