My friend (Muslim brother) messaged me that there was a vehicle for sale at a good price, however, it had a fuelling issue but was still drivable.

Question

My friend (Muslim brother) messaged me that there was a vehicle for sale at a good price, however, it had a fuelling issue but was still drivable. The seller of the vehicle told us that all we needed to do is service the fuel pump. Once this would be done the vehicle would run fine. The day after I purchased the vehicle (my friend did not contribute anything), my friend listed the vehicle with my consent and sold it. We told the new buyer about the problem. We managed to sell the vehicle and my friend took commission equal to half the profit. Two days later after the new owner had serviced the fuel pump the vehicle rode even worse. I ended up taking the vehicle back and refunding the money. The question is that my friend who took the commission said that he already spent the money and that he does not plan to pay me back due to his tough financial circumstances. Should my friend make an effort to pay me back or is he not obligated to?