The Book of Transactions (Kitab Al-Buyu`)
Muslim :: Book 10 : Hadith 3661
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.
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