A man mentioned to the Messenger of Allah ﷺ that he was deceived in a business transaction, whereupon Messenger of Allah ﷺ said: When you enter into a transaction, say: There should be no attempt to deceive. (Using translation from Muslim 1533a)

أَنَّهُ سَمِعَ ابْنَ عُمَرَ يَقُولُ ذُكِرَ رَجُلٌ لِرَسُولِ اللَّهِ ﷺ أَنَّهُ يُخْدَعُ فِي الْبُيُوعِ فَقَالَ لَهُ «مَنْ بَايَعْتَ فَقُلْ لَا خِلَابَةَ» وَكَانَ إِذَا بَايَعَ يَقُولُ لَا خِلَابَةَ