وعليكم السلام ورحمة الله وبركاته If the first party is obliged to buy then the sale has taken place even if you have not given him the bike yet and here we say yes , it is forbidden . Because obviously you made a profit out of lying . You said to that person that you would sell the bike to him for 12,000 while you do not own it ! That's why the Prophet صلى الله عليه وسلم forbade a man from selling what he did not own. He said in the narration of Abdullah Bin Umar : " لَا طَلَاقَ إِلَّا فِيمَا تَمْلِكُ، وَلَا عِتْقَ إِلَّا فِيمَا تَمْلِكُ، وَلَا بَيْعَ إِلَّا فِيمَا تَمْلِكُ وَلَا وَفَاءَ نَذْرٍ إِلَّا فِيمَا تَمْلِكُ ". Also, this type of sale causes a lot of problems But if it is simply an offer from you to the first party and he has the right to withdraw from the purchase and cancel the sale even after you have bought the bike then there is nothing wrong with that according to the correct opinion. Because there is no buying or selling between the two of you until you own the bike. And Allah عز وجل knows best.