Sahih Bukhari Volume 3, Book 34, Hadith Number 296.

Narated By Hakim bin Hizam : The Prophet aid, “The buyer and the seller have the option to cancel or to confirm the deal, as long as they have not parted or till they part, and if they spoke the truth and told each other the defects of the things, then blessings would be in their deal, and if they hid something and told lies, the blessing of the deal would be lost.”