Abu Al-Minhal said:"I asked Al-Bara bin 'Azib about money exchange. He said: 'Ask Zaid bin Arqam, for he is better than me and more knowledgeable.' So I asked Zaid and he said: 'Ask Al-Bara for he is better than me and more knowledgeable.' And they both said: 'The Messenger of Allah forbade (selling) silver for gold on credit

English translation · Sunan an-Nasa'i