Enter into transactions honestly and truthfully without attempting any deception.

This hadith emphasizes the importance of honesty and truthfulness when engaging in business transactions. It is narrated by Abdullah b. Dinar that he heard Ibn 'Umar say that a man mentioned to the Prophet Muhammad that he was deceived in a business transaction, to which the Prophet replied, "When you enter into a transaction, say 'There should be no attempt to deceive.'" This hadith teaches us that we should always strive for honesty and truthfulness when conducting any kind of business or financial dealings with others. We should not try to deceive or take advantage of someone else's trust or naivety for our own benefit; rather, we should always be honest and transparent with our dealings so as not to cause harm or distress to anyone else involved.