What is the ruling on dealing with a person by giving him part of the price of merchandise, on the condition that he receives the remainder of the price after selling it, along with granting him an additional amount for his efforts? And is it permissible to hold him responsible for the damage or theft of the merchandise?

This transaction has two possibilities:

First: That the person is an agent on your behalf for a known fee, which is 10 dollars for each phone. Taking a fee for agency is permissible, and the agent deserves it upon delivering the goods. The agent is not responsible for the phones during transit unless he commits an تجاوز (transgression) or تقصير (negligence). However, this agent is considered to be lending you the remaining price of the goods. This loan is tied to his entitlement to the agency fee, making it as if he stipulated his agency in exchange for lending to you. This is a benefit that corrupts the loan and makes it usurious (riba).

Second: That he is your partner with a share of the price of the goods on a Mudarabah (definition) basis. In this case, it is not permissible to set a specific amount of profit for him, such as the ten dollars. Instead, a common percentage of the profit must be agreed upon. In this case also, he does not guarantee the phones during transit unless he is negligent, because the hand of a partner is a hand of trust (yad amanah (definition)).