Musnad Ahmad 773:14

'Affan narrated to us, Sa'id ibn Zayd narrated to us, al-Zubayr ibn al-Khirrit narrated to us, from Abu Labid, who said: 'Urwah ibn Abi al-Ja'd al-Bariqi was staying among us. Abu Labid Limazah ibn Zabbar narrated from him, from 'Urwah ibn Abi al-Ja'd, who said: A caravan of goods was presented to the Prophet, may Allah bless him and grant him peace, so he gave me a dinar and said: "O 'Urwah, go to the caravan and buy a sheep for us." He said: So I went to the caravan and bargained with its owner, and I bought two sheep from him for a dinar. I came driving them—or he said: leading them—when a man met me and bargained with me, so I sold him one of the sheep for a dinar. I came with the dinar and I came with the sheep, and I said: "O Messenger of Allah, this is your dinar and this is your sheep." He said: "And how did you do it?" So I told him the story. He said: "O Allah, bless him in the transaction of his right hand." I have seen myself standing at the marketplace of Kufa, and I would make a profit of forty thousand before I reached my family. And he used to buy slave girls and sell them.