What is the ruling on a brother taking possession of a car and paying its installments after his brother purchased it through murabaha from an Islamic bank with the intention that the former would dispose of it?

If he bought a car through a sharia-compliant Murabaha transaction from the bank, there is no objection to selling it to his brother for the same price to enable him to pay its installments to the bank. This is a permissible Tawliyah (resale at cost) transaction, based on the statement of Ibn Qudamah: "And if he said: 'Let me be the trustee for what you bought at that price,' and he said: 'I have made you the trustee,' it is valid, provided the price is known to both of them."