Is it permissible for the tenant to pay a lump sum to the landlord, in addition to a lower-than-usual monthly rent, for leasing a shop for a specified period, and is this considered unlawful (haram) or lawful (halal)?

What the landlord asks from the tenant in addition to the monthly rent takes different forms:

1. A loan that yields a benefit: The landlord asks for a sum as a loan to be repaid at the end of the contract in exchange for reducing the rent. This is forbidden because it is "a loan that yields a benefit." 2. A sum in exchange for reducing the rent and perpetualizing the contract: The landlord asks for a sum in exchange for reducing the rent and making the lease contract perpetual. This contract is forbidden and void, because a lease (ijarah) cannot be perpetual; rather, its duration must be specified. 3. An upfront sum with reduced rent and a specified duration: The landlord asks for an upfront sum with a reduction in rent and a specified contract duration. This is permissible, provided that the paid amount is accounted for as part of the rent in case the contract is terminated due to unforeseen circumstances.