What is the ruling on enrolling in an educational institute that offers two payment options: either paying in cash at a reduced price, or in installments at a higher price?

If the institute agrees with the student on a specific fee, whether in cash or installments, there is no objection to that. However, if the payment method is not agreed upon before the contract, it is not permissible, because it falls under the category of "two sales in one sale" and leads to gharar (uncertainty) which is forbidden by Islamic law, based on the Prophet's (peace be upon him) saying: "Whoever makes two sales in one sale, then he gets the lesser of them or usury." This ruling applies to ijarah (leasing/hiring) just as it applies to bay' (selling).