From Sahih Muslim (Hadith 3860):
Abdullah b. Dinar narrated that he heard Ibn 'Umar (Allah be pleased with them) saying:A man mentioned to the Messenger of Allah (ﷺ) that he was deceived in a business transaction, whereupon Allah's Messenger (ﷺ) said: When you enter into a transaction, say: There should be no attempt to deceive
Reference: Muslim 3860