Urwah bin Abi al-Ja'd al-Bariqi (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) gave me a dinar and said: "Buy a sheep for us with it." He said: I went and bought two sheep for one dinar. A man met me on the way and bargained with me for a sheep, so I sold it to him for a dinar. I came to the Prophet (peace and blessings be upon him) and said: "This is your dinar and this is your sheep." The Prophet (peace and blessings be upon him) asked: "How did you do that?" He told him, and he (peace and blessings be upon him) supplicated: 'Allahumma barik lahu fi safqati yaminihi' (O Allah, bless him in the dealings of his right hand). Urwah (may Allah be pleased with him) said: I would stand in the Kunasah (market yard) of Kufah, and I would not return home until I had made a profit of forty thousand.
A group narrated it from Sa'id bin Zayd, the brother of Hammad bin Zayd, and he is not strong.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب القراض / 11617