What is the ruling on working for a loan company that claims legitimacy, yet relies on selling a commodity to the client, and the client authorizing the company to sell it to a third party (a child aged 8 years old) who authorized the company owner, then the company buys the commodity from the third party and sells it to the client again, while rotating the same commodity to all clients?

If the merchandise is returned to the company for less than the price at which it was sold to the customer, then this is not permissible because it falls under Bay' al-Inah (sale and buyback arrangement), and the merchandise here is a means to usury (riba). Imam Ahmad explicitly stated that it is not permissible for the seller to buy back his merchandise which he sold for less than the price he sold it for, though it is permissible for more. This is conditional on there being no prior agreement or trickery. If the questioner works for the company and assists in this transaction, her work is not permissible due to the general prohibition of cooperating in sin and aggression.