That there was a man who was not very sensible and he would make purchases. So his family came to the Prophet ﷺ and said: "O Messenger of Allah! Stop him (from making purchases)." So Allah's Prophet ﷺ called him to prohibit him, and he said: "O Messenger of Allah! I have no patience for business." So he said: "When you are buying, say: 'Hand to hand, and no cheating.'"  

أَنَّ رَجُلاً كَانَ فِي عُقْدَتِهِ ضَعْفٌ وَكَانَ يُبَايِعُ وَأَنَّ أَهْلَهُ أَتَوُا النَّبِيَّ ﷺ فَقَالُوا يَا رَسُولَ اللَّهِ احْجُرْ عَلَيْهِ فَدَعَاهُ نَبِيُّ اللَّهِ ﷺ فَنَهَاهُ فَقَالَ يَا رَسُولَ اللَّهِ إِنِّي لاَ أَصْبِرُ عَنِ الْبَيْعِ فَقَالَ إِذَا بَايَعْتَ فَقُلْ هَاءَ وَهَاءَ وَلاَ خِلاَبَةَ