Is the financial penalty for late payment of rent considered usury (riba), and is paying the rent on time without incurring the penalty considered engaging in usury?

The summary of the answer:

The landlord owns the rent of the house by virtue of the contract, and it becomes a debt owed by the tenant. It is not permissible for the landlord to stipulate a financial penalty on the tenant in case of late payment, as this is usury (riba), which is forbidden. If the contract includes a condition for a late payment penalty, then the contract is forbidden, and it is not permissible to enter into it.