Is it permissible to sell a debt, such as converting a debt owed by a cement company into cement, and then selling this cement before taking possession of it?

The question included two issues: selling a debt to the debtor, and selling an item before taking possession of it.

Selling a debt to the debtor for compensation is permissible, provided that the creditor takes possession of the compensation (the cement) in the same session of the contract for the sale to be valid. Otherwise, it is the impermissible selling of debt for debt, which is forbidden by consensus.

Selling a movable item (cement) before taking possession of it is not permissible according to the majority of scholars, due to the Prophet's (peace be upon him) prohibition of it.

In summary, selling the debt to the company is permissible, provided that the cement is taken possession of in the same session, and it is not permissible to sell it before taking possession of it.