What is the ruling on subscribing to a social solidarity fund that deducts one day's salary monthly from the subscriber and invests these funds in deposits with Islamic banks, and pays the subscriber upon termination of their service a fixed amount equivalent to fifteen days' salary for each year of subscription, regardless of the profit or loss of the fund's investments?

Participation in this fund is impermissible because the participant benefits from it in an usurious manner. The percentage he will receive is fixed and known beforehand; it does not increase or decrease, regardless of whether the fund's projects profit or lose. This is the very interest (usury) dealt with by commercial banks, and it is usury (riba), as decided by contemporary Fiqh academies and the majority of scholars. What some contemporary scholars have permitted regarding employee associations are cooperative funds established for the purpose of lending to participants or assisting them in emergency situations and the like.