Abu Ishaq (may Allah have mercy on him) says that my wife and the umm walad of Zayd bin Arqam (may Allah be pleased with him) went to Sayyidah Aishah (may Allah be pleased with her), and the umm walad of Zayd bin Arqam said: I sold Zayd a slave for 800 dirhams on credit, then I bought him back from him for 600 dirhams in cash. Sayyidah Aishah (may Allah be pleased with her) said: Tell Zayd (may Allah be pleased with him) from me that you have nullified even the jihad you did with the Messenger of Allah (peace and blessings be upon him), unless you repent. Evil is what you sold and evil is what you bought.
Shu'bah narrated it like this, by way of irsal (with a broken chain).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10798