Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: We were waiting for the Messenger of Allah (peace and blessings be upon him) at his door. He (peace and blessings be upon him) came out and we followed him, until he came to one of the mountain passes of Madinah and sat down there. He (peace and blessings be upon him) said: "Let no one go out of the town to meet a trade caravan, and let no Muhajir sell on behalf of a Bedouin. Whoever buys an animal whose milk has been held back has the option for three days. If he returns it, (he should give) the like of it as well," or he said: "twice its (milk) in wheat, that is, wheat equal to twice its milk."
Only Jumay' bin Umayr narrated it; al-Bukhari said: There is some question about him (fihi nazar).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10723