Sunan at-Tirmithiy كتاب البيوع باب ما جاء فى كراهية بيع ما ليس عندك
Ḥakīm Ibn-Ḥizām went to the Messenger of God, peace and blessings of God be upon him, and said, "Men come to me asking to buy things that I do not have. Should I conclude the sale, then buy [the goods] from the market, and deliver to them?" The Messenger of God, peace and blessings of God be upon him, replied, "Do not sell what you do not have(1)." Footnotes: (1) I.e., money should not pass hands without the merchandise present. Click on ḥadīth to read more
The Messenger of God, peace and blessings of God be upon him, said, "It is not permissible to couple a loan with a sale (1), nor to set two conditions for a sale, nor to make a profit on what is not yet garanteed (2), nor to sell what you do not own." Footnotes: (1) i.e. to make one conditional upon the other. (2) by selling goods you have bought before they are delivered to you. Click on ḥadīth to read more