Is it considered usury for a person to buy a commodity and then sell it in installments at a price higher than its purchase price?

Murabaha to the one who promises to purchase is permissible if the agent buys the commodity and takes possession of it physically before selling it to the one who promised to purchase. It is not permissible for the owner of the capital to profit from what he has not guaranteed, and if he has not acquired the commodity and it has not entered into his responsibility, then it is not permissible for him to sell it.