Validity of giving a promise to buy before actual buying

A: When a person sells a car to someone else before taking possession of it, the sale is invalid. This act is impermissible whether the car is sold by cash or deferred payment; whether the profit is a percentage of the purchase price such as the third or a specific value; or whether a down payment is paid or not. This is so because he sells it before possessing it. On the other hand, when he agrees with the other person to sell it to him after acquiring and taking possession of the car, the sale is permissible because this is a promise of buying, not a contract. They then have the right to conclude a contract so as to keep the promise. The second party may sell it to someone else, and the first party may buy a different car. (Part No. 13; Page No. 238)  May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions!