Narrated by Sayyiduna Hakim bin Hizam (may Allah be pleased with him), he says: I said, "O Messenger of Allah! When I buy some things, which of them are lawful for me and which are unlawful?" The Prophet (peace and blessings be upon him) said: "When you buy something, do not sell it further until you have taken possession of it."
Hadith Referenceالفتح الربانی / كتاب البيوع والكسب والمعاش وما يتعلق بالتجارة / 5879