Entitlement to profit:

No one is entitled to profit unless he invests money, does the work or undertakes liability.

In that case, he is entitled to the profit, because it is the growth of the wealth, so it belongs to the owner of that wealth.

For that reason the owner of the wealth is entitled to a share of the profit in the case of mudaarabah [a partnership in which one partner invest capital and the other invests his labour].

Entitlement to a share of the profit is deserved if someone works and puts in effort, as in the case of the one who does the work in a mudaarabah partnership, so he is entitled to a share of the profits.

This is similar to the concept of hiring someone to do work.

A person may also be entitled to a share of the profits in return for undertaking liability, as in the case of a partnership where each partner has full authority and full liability, because the Prophet (blessings and peace of Allah be upon him) said:

“Profit is by virtue of liability” or “The proceeds are by virtue of liability.”

In other words, whoever is liable has a right to the proceeds.

Hence it is permissible for a person to take on work – such as sewing a garment –for a certain fee, then agree with someone else to do this work for a fee lower than what he is going to be paid, and to take the difference as a lawful profit, for the simple reason that he is liable for the work, even though he is not going to do any of the work himself, and perhaps he has no wealth of his own at all.

If none of these three scenarios apply, in which a person is only entitled to profit because of one of them, then there is no way that he may be entitled to take any profit.

Hence, it is not right for one person to say to another, Use (invest) your wealth on condition that the profit will be mine, or the profit will be shared between us.

This is nonsense according to all the fuqaha’.

The profit belongs to the owner of the wealth, without anyone else having the right to any claim on it.

End quote. al-Mawsoo‘ah al-Fiqhiyyah (26/60)