What is the legal ruling on working for an agricultural company that stipulates charging interest to the customer in case of delayed payment of due installments, even though it may sometimes be waived, in order to ensure their commitment to payment?

It is not permissible to stipulate a financial penalty on the buyer for late payment of the price. This is a usurious condition, forbidden and void, whether it is a pre-stipulated condition or not. It is not permissible to work in anything directly related to imposing this forbidden penalty, as it involves assisting in sin. However, if the work in the company is not directly related to imposing this penalty, then there is no objection to it. Such a condition can be dispensed with through lawful means such as a guarantee (kafalah (definition)), collateral (daman), pledge (rahn), or stipulating the annulment of the contract upon delay.