Is it permissible for a father to lease a shop he rented 30 years ago—and for which he hasn't paid rent for three years—to another person to convert it into a restaurant, without the knowledge of the original lessor?

It is permissible for the lessee to sublease the leased property without the lessor's knowledge if this occurs during the contract period, and if the sublessee benefits from it in a manner similar to or less damaging than the original lessee's use, provided that the harm caused by the new sublessee does not exceed the harm caused by the first lessee. This is also contingent on the lessor not having stipulated that the lessee must utilize the benefit personally. It is not permissible to sublease it to someone who would cause more harm, or whose use would contradict the harm caused by the first lessee. Therefore, it is not permissible to sublease a car repair shop to be used as a restaurant except with the owner's permission.