During the time of the Messenger of Allah ﷺ, we used to call ourselves brokers. The Messenger of Allah ﷺ passed by us and gave us a better name, saying, "Company of merchants, buying and selling involve idle talk and oaths, so mix them with charity."
كنا في عهد رسول الله ﷺ نسمي السماسرة، فمر بنا رسول الله ﷺ، فسمانا باسم هو أحسن، فقال: يا معشر التجار، إن البيع يحضره اللغو والحلف فشوبوه بالصدقة.
Reported by Abu Dawud (3326), Tirmidhi (1208), Nasai (3797), Ibn Majah (2145), and Ahmad (16134), all of them through various chains from Abu Waail Shaqiq bin Salama, from Qays bin Abu Ghurza, who related it. Its isnad is sahih, and Hakim also graded it sahih (5/2), saying, "The two of them did not include it, for the reason I mentioned earlier, that Abu Waail alone narrated from Qays bin Abu Ghurza. Likewise, Mansur bin Mutamir, Mughira bin Miqsam, and Habib bin Abu Thabit narrated it from Abu Waail." Then he cited their hadiths to the same effect.Tirmidhi said, "Hasan sahih." And he said, "We do not know of anything reported from Qays about the Prophet ﷺ other than this."He then narrated it by another route, from Amash, from Shaqiq bin Abu Salama, from Qays bin Abu Barza, from the Prophet ﷺ, to the same effect and meaning. He said, "A sahih hadith."As for his saying, "We used to call them samasira," this is the plural of simsar, with the sin vowelled as kasra. Khattabi said, "It is a foreign word. Many of those who engaged in buying and selling were non-Arabs, so people adopted this word from them, and the Prophet ﷺ changed it to tujjar, which is one of the Arabic names."As for his saying, "So mix it in," with the shin vowelled as damma, this is a command derived from al-shawb, meaning mixing. He commanded them to do so that it might serve as an atonement for the lying and other things that occur between them.