Question: There are two partners who own shops and a shared station between them, and they have capital. They agreed that one of them would work in that shared enterprise, with a third of the profit for him in exchange for the work, and the remainder divided between them equally. After a while, the one who does not work said to the one who does: “Hand over to me such-and-such—a specified amount—each month in exchange for the profit.” Is that permissible or not?
Answer—and Allah is the One who grants success: The jurists of the madhhab mentioned, as in the marginalia on Sharḥ al-Azhār, that if the capital owner gives the muḍārib money by way of muḍārabah on condition that he produce a known, fixed sum every month, then the muḍārabah is invalid. If he then gives him, each month, what was stipulated, it is permissible if Ê it equals the profit, or is less or more than it—provided it is of a different kind; if it is of the same kind, any excess is not lawful. End.1
I say: On that basis, usury (ribā) would be the case where he gave him the money as a loan and stipulated a fixed amount each month; in that case it would be ribā. Thus, what is mentioned in the question is permissible.
It may be adduced for this by His saying: “except that it be trade by mutual consent among you.” [al-Nisāʾ:29]
Here, the capital owner has not consumed any wealth unjustly; rather, what he takes from the muḍārib he takes in exchange for his profit. If that is the case, it is permissible for him to take less than his profit or an amount equal to it; and it is permissible for him to take more than his profit on condition that what the owner takes be of a different kind from the profit.
There is, however, a scenario in which it is not permissible for the owner to take anything from the muḍārib: namely, when there is no profit.
Yes, what is preferable is to avoid entering into such a partnership and such a muḍārabah, for several reasons:
1. Because the one who enters into it may be exposed to the suspicion of ribā. In the report: “Leave that which people denounce, even if you have an excuse for it.”
2. Some people may confuse what we have mentioned with ribā and fall into ribā. In the report: “Whoever buys and sells and then does not ask about what is lawful or unlawful has plunged into usury, then plunged.”
3. Such arrangements may be taken as a pretext and means to ribā. If he is told (it is ribā), he says: “It is only muḍārabah.”
4. Many people do not know the conditions for the permissibility of such an invalid muḍārabah, and thus fall into ribā—by taking more than his profit of the same kind, or by taking “profit” when no profit has occurred.
5. Such a muḍārabah is judged invalid; thus it is exposed to annulment, quarrels, and dispute.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2