Sahih Muslim Book 10, Hadith Number 3661.

Chapter : Truthfulness in transaction and description (of the defect in the commodity).

Hakim b. Hazim (Allah be pleased with him) reported Allah’s Messenger(may peace be upon him) as saying: Both parties in a business transaction have the right to annul it so long as they have not separated; and if they speak the truth and make everything clear they will be blessed in their transaction; but if they tell a lie and conceal anything the blessing on their transaction will be blotted out.