Makhul (may Allah have mercy on him) narrates as a marfu' report that the Prophet (peace and blessings be upon him) said: "Whoever buys something without having seen it has the option when he sees it: if he wishes he may take it, and if he wishes he may leave it."
This is mursal, and Abu Bakr bin Abi Maryam is da'if (weak); Abu Bakr bin al-Harith and others told me this from Ali bin Umar Abu al-Hasan al-Daraqutni al-Hafiz (may Allah have mercy on him). It has also been narrated through another route from the Prophet (peace and blessings be upon him), and it is not authentic.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10425