It is invalid to sell goods before taking possession of them Sahih Muslim 1526 b, 1527 b
Translation
Ibn Umar (Allah be pleased with them) reported Allah's Messenger (ﷺ) as saying
He who buys foodgrain should not sell that before taking possession of it. He (the narrator) said: We used to buy foodgrain from the caravans in bulk, but Allah's Messenger (ﷺ) forbade us to re-sell that until we had shifted it to some other place.