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.

أَنَّهُ سَمِعَ ابْنَ عُمَرَ يَقُولُ ذَكَرَ رَجُلٌ لِرَسُولِ اللَّهِ ﷺ أَنَّهُ يُخْدَعُ فِي الْبُيُوعِ فَقَالَ رَسُولُ اللَّهِ ﷺ مَنْ بَايَعْتَ فَقُلْ لاَ خِلاَبَةَ فَكَانَ إِذَا بَايَعَ يَقُولُ لاَ خِيَابَةَ

There should be no attempt to deceive."

عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ بِهَذَا الإِسْنَادِ مِثْلَهُ وَلَيْسَ فِي حَدِيثِهِمَا فَكَانَ إِذَا بَايَعَ يَقُولُ لاَ خِيَابَةَ