Is it permissible to sell trees that bear fruit annually for five years using the Salam (forward) contract, with the stipulation of a specific weight for the fruits and the provision of real estate guarantees equal to the price, and is it permissible to guarantee the sale of the crop at a price that ensures profit for the buyer through a third party?

The question is unclear. For the sake of benefit, we will provide an answer: A contract for a described fruit that is a deferred obligation, where its availability at the agreed-upon time is highly probable, is considered a salaf (forward) sale, and it is permissible. There is no harm in providing guarantees to the buyer, such as mortgaging property, because the muslam fih (the object of the salaf sale) is a debt owed by the seller, and the creditor has the right to request security for his debt. As for guaranteeing the sale of the harvest, if it means that a third party promises the buyer to purchase the fruit from him and guarantee his profit from it, or to enter into a parallel salaf contract with him for a described fruit that is a deferred obligation with the same delivery date, then there is no harm in that. If something else is intended, please clarify.