If an item is not available in one’s own shop but is available in the market or at a nearby shop, is it permissible to make a deal or sell it? What is the ruling on taking an advance payment for it? And is it valid to fix the price in such a case or not?
Selling an unowned item in the manner described is not permissible according to Shariah. However, if a promise of sale is made, and once the item is available a formal offer and acceptance are carried out, then it is undoubtedly permissible and this is the correct way to do it.
کمافی الشامیۃ: وشرط المعقود عليه ستة: كونه موجودا مالا متقوما مملوكا في نفسه، وكون الملك للبائع فيما يبيعه لنفسه، وكونه مقدور التسليم فلم ينعقد بيع المعدوم(الیٰ قولہ)ولا بيع ما ليس مملوكا له وإن ملكه بعده اھ(4/505)۔