An Nasai: Hadith 4576

"Ubadah bin As-Samit and Muawiyah met at a stopping place on the road. 'Ubadah told them: 'The Messenger of Allah forbade selling gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates"'- one of them said: 'salt for salt,"' but the other did not say it-"unless it was like for like, hand to hand. And he commanded us to sell gold for silver and silver for gold, and wheat for barley and barley for wheat, and to hand, however we wanted."' And one of them said: "Whoever gives more or ask for more has engaged in Riba."'