Al-Ala narrates from his father that he said: I came to Uthman bin Affan (may Allah be pleased with him) and said to him: "Goods have arrived; will you give me money so that I may buy them?" He said: "Will you do it?" He said: "Yes, but I am a mukatab (a slave contracted to buy his freedom); so I will buy it on the condition that the profit is shared between me and you." He replied, "Yes." Then Uthman (may Allah be pleased with him) gave me money on that condition.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشفعة / 11607