Musnad Ahmad 285:6

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Shaqiq, from Qays ibn Abi Gharzah, who said: We used to be called "the brokers" during the time of the Messenger of Allah, peace and blessings of Allah be upon him. The Messenger of Allah, peace and blessings of Allah be upon him, passed by us and named us with a name that was better than it. He said: "O assembly of merchants, this selling is attended by vain talk and swearing, so mix it with charity."