[A Man Bought a Truck and Gave It to Another on the Basis That, After Reimbursing the Price, It Would Be Shared Between Them Half-and-Half]

Answer—and Allah is the One who grants success: What appears to me is that the transaction is permissible. That is because the truck driver is entitled to half of the truck’s yield; when he has fully reimbursed its price to the purchaser, he becomes entitled to half of the truck—since by his work he is entitled to half of the income.
If it is said: The contract is invalid because the partnership in the vehicle between the two men entailed transferring to the driver half of the vehicle in the future, and that is among what vitiates contracts.
We say: The settled principle is to construe Muslims’ contracts as valid wherever possible; and here validity is possible. We say: the contract is to be construed as intending the transfer to the driver of half the truck from the moment of contract, in exchange for a benefit that is the price—namely, that he works as its driver until he reimburses its price to the purchaser. If the contract is carried upon this (construction), there is nothing in it that vitiates it. This is what has appeared, and Allah knows best. Praise be to Allah, Lord of the worlds.
If it is said:
1. What is the ruling if the driver worked for a period of time, then something befell him that prevented him from continuing, leading to the rescission of the contract?
2. What is the ruling if the truck suffers an accident that disables it completely?
3. What is the ruling regarding the fuel, oils, tires, spare parts, and so on that the truck requires?
We say:
1. If something occurs to the driver that prevents him from continuing the work and the two parties mutually rescind, then the driver is entitled to the wage of one of equal service (ujrat al-mithl). This is what custom has established for truck drivers: either he is given, for his work, monthly salaries of a certain amount for each month, or he is given a specified share of the income obtained, according to what custom has established.
2. If the truck is completely disabled, then the driver is entitled—as we mentioned first—either to monthly salaries or to a share of the income obtained.
3. Everything the vehicle needs of fuel, oils, maintenance, and spare parts and other than that is to be from the truck’s income, whether or not that is mentioned in the contract; for custom and usage run upon that.
If the two parties reached an agreement contrary to what custom has established, then what is obligatory is to act upon that agreement and be bound by it.
If it is said: What does the driver guarantee of defect, fault, or damage that occurs to the truck?
We say: The driver guarantees what occurs to the truck due to his negligence or his transgression against the vehicle—such as parking it in a place where he knows or suspects that there is danger, yet he parks it there. If it is exposed to what is feared in that place, then liability falls upon it (the vehicle) and upon the driver; he guarantees that from his personal funds.
— If something happens to it in that place from a cause not feared in that place, then the driver does not guarantee it.
— We have said that because the truck is in the driver’s hand as a trust; the driver is a trustee, and the trustee is not liable for what occurs to the trust except what is due to his negligence or his transgression— for that he is liable. Allah Most High said, “There is no blame upon the doers of good.” [al-Tawbah:91]
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2