Sahih Muslim | Book 10 | Hadith Number 3646

Narrated by Ibn Umar (Allah be pleased with them)
Ibn Umar (Allah be pleased with them) reported Allah's Messenger (may peace be upon him) as saying: He who buys food-grain should not sell that before taking possession of it. He (the narrator) said: We used to buy food-grain from the caravans in bulk, but Allah's Messenger (may peace be upon him) forbade us to re-sell that until we had shifted it to some other place.