Yahya related to me from Malik from Abdullah ibn Dinar fromAbdullah ibn Umar that a man mentioned to the Messenger of Allah, mayAllah bless him and grant him peace, that he was always being cheatedin business transactions. The Messenger of Allah, may Allah bless himand grant him peace, said, "When you enter a transaction, say, 'Notrickery.' So whenever that man entered a transaction, he would say,'No trickery.' "
USC-MSA web (English) reference: Book 31, Hadith 99
Arabic reference: Book 31, Hadith 1385