Hadith 44:15
It was narrated that Qays bin Abi Gharazah said:
"We used to trade in the markets of Al-Madinah and we used to call ourselves as-Samasir (brokers) and the people called us that, but the Messenger of Allah came out to s and called us by a name that was better than what we called ourselves. He said: "O merchants (Tujjar)! Selling involves (false) oaths and idle talk, so mix some charity with it,"" (Sahih )
أَخْبَرَنِي مُحَمَّدُ بْنُ قُدَامَةَ، عَنْ جَرِيرٍ، عَنْ مَنْصُورٍ، عَنْ أَبِي وَائِلٍ، عَنْ قَيْسِ بْنِ أَبِي غَرَزَةَ، قَالَ كُنَّا بِالْمَدِينَةِ نَبِيعُ الأَوْسَاقَ وَنَبْتَاعُهَا وَنُسَمِّي أَنْفُسَنَا السَّمَاسِرَةَ وَيُسَمِّينَا النَّاسُ فَخَرَجَ إِلَيْنَا رَسُولُ اللَّهِ صلى الله عليه وسلم فَسَمَّانَا بِاسْمٍ هُوَ خَيْرٌ لَنَا مِنَ الَّذِي سَمَّيْنَا بِهِ أَنْفُسَنَا فَقَالَ " يَا مَعْشَرَ التُّجَّارِ إِنَّهُ يَشْهَدُ بَيْعَكُمُ الْحَلِفُ وَاللَّغْوُ فَشُوبُوهُ بِالصَّدَقَةِ "
Original Reference: Sunan an-Nasa'i 4463