The ruling on selling the produce of a farm for future years

Question:
Is it permissible for me to buy the produce of a farm with date palms for several years to come, on the condition that we agree on the price now in the contract? And in this case, is the zakah due on the buyer or on the owner of the farm?

Answer:
This is not permissible; it is not permissible to sell future fruits, meaning this is selling something unknown. However, salam (a forward sale paid in advance) is fine if he receives money from you on the condition that he pays you every year, and it is not permissible for more than two years, meaning up to two years, he pays you a sum of dates or grains every year. This is called salam. There is no harm, there is no harm if they have a loan (sarf). Yes.