Musannaf Ibn Abi Shayba 13:2239

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Al-A’mash narrated to us, from Shaqiq, from Qays ibn Abi Gharzah, who said: We used to trade in the markets of Medina, and we used to call ourselves "the brokers" (as-samasirah). We came to the Prophet, peace and blessings of Allah be upon him, and he named us with a name that was better than what we used to call ourselves. He said: "O assembly of merchants, this selling is attended by vain talk and swearing, so mix it with charity."