Conditions of Partnership in Trade and the Invalidity of the Condition to Return the Capital

Question:
May Allah reward you with good and do you well. He says: I am partnering with a person in a taxi for a share of the profit and loss, for a period of only two years, after which the partnership between us ends. I paid him the value of this share on the condition that he return it as it is, without increase or decrease, after these two years have ended. Is this considered riba (usury or interest), and what is the evidence?

Answer:
Yes, partnership in cars or in other things, with a share of the produce, a common share of the produce from the trade profit or from the earnings of the cars or other rented assets, all of this is permissible, and praise be to Allah. However, a specific amount of money is not stipulated; rather, the partnership is by a common share, such as a quarter, a half, a tenth, or a fifth, so that everyone is equal in increase and decrease. If there is an increase, everyone takes his share from it; if there is a decrease, it is borne by everyone. As for specifying a certain amount, this is not permissible. Likewise, if it is stipulated that the capital be returned without any decrease, this is a condition that is not permissible and it invalidates the partnership, because the partnership may suffer a loss due to bankruptcy, in which case the capital or part of it is lost. It is exposed to loss and profit, and exposed to destruction. If it is destroyed without negligence on the part of the worker, he is not liable for compensation; he is only liable if he was negligent and the destruction was due to his negligence. Stipulating that the capital be returned absolutely, whether there is profit or not, is an invalid condition. Yes.