Silsilat al-Ahadith al-Sahihah

Muhammad bin Yahya bin Hibban says: Munqidh bin Amr was my grandfather. Some affliction befell his head which affected his tongue, but despite this he did not refrain from trading and was always deceived. He came to the Prophet (peace and blessings of Allah be upon him) and told him the whole matter. The Prophet (peace and blessings of Allah be upon him) said: "When you make a deal, say: 'No deception.' Then, for whatever goods you buy, you have the option for three nights; if you like it, keep it, and if you dislike it, return it to the owner."