Abu Dawud
Commercial Transactions
Book Number: 016 / Hadith Number: 3320
Narated By Qays ibn AbuGharazah : In the time of the Apostle of Allah (pbuh) we used to be called brokers, but the Prophet (pbuh) came upon us one day, and called us by a better name than that, saying: O company of merchants, unprofitable speech and swearing takes place in business dealings, so mix it with sadaqah (alms).