What is the ruling on stipulating financial penalties for members in the event of delay in paying monthly subscriptions, or withdrawal from the group, or upon joining it, within an agreement for collecting and investing funds?

The basic principle concerning conditions is that they are permissible and must be fulfilled, unless they contradict Islamic law. This includes penalty clauses, with the exception of penalty clauses for delayed payment of debts, as these constitute usury (riba). However, the installments paid by a partner do not constitute a debt; therefore, it is permissible to charge additional fees for a delayed installment payment. Similarly, it is permissible to impose fees for a new partner joining or an existing partner leaving, because the fundamental principle in financial transactions is permissibility and lawfulness.