Hakim bin Hizam (may Allah be pleased with him) said: I said: O Messenger of Allah (peace and blessings be upon him)! I am a man who buys goods; what of that is lawful and what is unlawful? He (peace and blessings be upon him) said: "O son of my brother! When you buy goods, do not sell them before taking possession of them."
Yahya bin Abi Kathir did not hear it from Yusuf; he only heard it from Ya'la bin Hakim, from Yusuf.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10684