Bakr bin Abdullah al-Muzani narrates that Sayyiduna Ibn Abbas (may Allah be pleased with them both) came from Madinah to Makkah, and I was with him. He praised and extolled Allah, the Mighty and Majestic, then said: O people, there is no harm in sarf (currency exchange) as long as it is hand to hand; usury (riba) is only in deferred payment. This statement spread among the people of the East and the West, until, when the Hajj season ended, Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) came to him (Ibn Abbas, may Allah be pleased with them both) and said: O Ibn Abbas, have you consumed usury and fed it to others? He said: Have I done so? Abu Sa'id said: Yes. The Messenger of Allah (peace and blessings be upon him) said: "Gold for gold, weight for weight, like for like, its raw ore and its coined gold (alike); whoever gives more or asks for more has dealt in usury. And silver for silver, weight for weight, like for like, its raw and its coined (alike); whoever gives more or asks for more has dealt in usury. And barley for barley, dates for dates, and salt for salt, like for like; whoever gives more or asks for more has dealt in usury." Then, when the following year came, Ibn Abbas came, and I went with him. He praised and extolled Allah, then said: O people, last year I said something from my own opinion, and I seek Allah's forgiveness for it and repent to Him. Indeed, the Messenger of Allah (peace and blessings be upon him) said: "Gold for gold, weight for weight, like for like, raw and coined (alike); whoever gives more and asks for more has dealt in usury." And he repeated to the people (the ruling on) these six kinds.
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 456