What is the ruling on a person directing another to invest his money in a specific project, with profits shared between them, in exchange for the director guaranteeing the owner's capital by paying advance compensation for any loss?

If the intent of the question is that a person who does not possess money takes money from its owner on the basis of Mudarabah (profit-sharing partnership), such that he invests it for him in a project or trade, and they divide the profits according to a known percentage, then this is a permissible, lawful Mudarabah.

However, for the Mudarabah to be valid, the following conditions must be met: 1. The Mudarib (investor/manager) must not guarantee the capital against loss to the owner, because the loss is borne by the رب المال (owner of the capital). This condition is void and invalidates the contract. 2. The عامل (Mudarib) must have absolute discretion in managing the Mudarabah capital and independent control over it, and not be restricted such that his role is limited to mere advising.

Thus, the aforementioned transaction is invalid due to conditions that violate Islamic law. The Mudarabah must be conducted in its correct, lawful manner.