What is the ruling of Islamic law on the aforementioned partnership contract, and to what extent is the third partner entitled to the company's assets and what he received from the sale of the land and the car, taking into account the non-fulfillment of the agreed-upon condition (unwritten) regarding the compensation of capital and his distortion of the contract and his departure from the project?

It is not permissible for the capital owner to stipulate to the worker or partner a guarantee of the capital or a specific percentage of the profits. Furthermore, the partnership mentioned in the question is invalid because the third partner stipulated a percentage of the company's assets in exchange for his expertise (know-how), meaning his share is neither cash nor goods, but rather the benefit of the idea. The majority of scholars stipulate that for a partnership to be valid, the capital of each partner must be in cash, not goods or benefits. Malik and Ahmad, in one of two narrations, held it permissible for goods, provided they are valued. If the partnership is invalid, it must be dissolved, and each partner returns what they contributed. The owner of the idea is entitled to the value of his idea and a fair wage for his work, as estimated by experts.