Narrated Nafi':
Ibn 'Umar and I went to Abu Sa'eed and he narrated to us: 'the Messenger of Allah (ﷺ) said - and I heard him with these [two] ears: Do not sell gold for gold except kind for kind, nor sliver for silver except kind for kind, do not exchange more of one than the other, and do not sell what is not present from them for what is present.
[Abu 'Eisa said:] There are narrations on this topic from Abu Bakr, 'Umar, 'Uthman, Abu Hurairah, Hisham bin 'Amir, Al-Bara', Zaid bin Arqam, Fadalah bin 'Ubaid, Abu Bakrah, Ibn 'Umar, Abu Ad-Darda', and Bilal.
[He said:] The Hadith of Abu Sa'eed, from the Prophet (ﷺ) [about Riba] is a Hasan Sahih Hadith.
This is acted upon according to the people of knowledge among the Companions of the Prophet (ﷺ) and others, except for what has been related from Ibn 'Abbas; he did not see any harm in exchanging gold for gold or silver for silver, more for less, when it is done hand in hand, and he said: Riba' is only in credit. Similar it has been related from some of his companions. It has been related that Ibn 'Abbas changed his opinion when Abu Sa'eed narrated it to him from the Prophet (ﷺ). The first view is more correct.
And this is acted upon according to the people of knowledge [among the Companions of the Prophet (ﷺ) and others]. It is the view of Sufyan Ath-Thawri, Ibn Al-Mubarak, Ash-Shafi'i, Ahmad, and Ishaq. It has been reported that Ibn Al-Mubarak said: There is no difference over exchange.