Sahih Al Bukhari Hadith Number 2407

Narrated Ibn `Umar: A man came to the Prophet (peace be upon him) and said, “I am often betrayed in bargaining.” The Prophet (peace be upon him) advised him, “When you buy something, say (to the seller), ‘No deception.” The man used to say so afterwards.

43  Loans, Payment of Loans, Freezing of Property, Bankruptcy
Hadith number 2407
Volume no 3
Chapter: 19 (Wasting money)