What is the ruling on a bank loan in which the bank is authorized to buy and sell the commodity, and is this considered a circumvention of the ruling of "money for money"?

What we understand from the question is that the client buys a car from the bank for a deferred price, and then authorizes the bank to sell it in the same contract (first possibility), or stipulates that the bank sell it (second possibility).

According to the first possibility (sale and authorization): The sale is valid, but the authorization is void, because he authorized the sale of something he does not yet own. The bank's action is considered a fuduli (unauthorized) sale, which is valid according to the Hanafis, Malikis, and one narration from Ahmad, but void according to the Shafi'is and the relied-upon position of the Hanbalis.

According to the second possibility (sale with a condition): If the condition is consistent with the contract's requirements, or serves a benefit for the contracting party, or does not lead to a dispute, then the contract is valid. However, if it contradicts the essence of the contract (such as selling a slave with the condition that he not be sold), then the sale is void.

One must beware of selling the commodity back to the original seller as a trick to engage in riba (usury), as mentioned in the "issue of tawarruq," which has been prohibited.