Ata' b. Abu Rabah reported:Abu Sa'id al-Khudri (Allah be pleased with them) met Ibn 'Abbas (Allah be pleased with them) and said to him: What do you say in regard to the conversion (of commodities or money) did you hear it from Allah's Messenger (ﷺ), or is it something which you found In Allah's Book, Majestic and Glorious? Thereupon Ibn Abbas (Allah be pleated with them) said: I don't say that. So far at Allah's Massenger (ﷺ) is concerned, you know him better, and to far as the Book of Allah to concerned, I do not know it (more than you do), but 'Usama b. Zaid (Allah be pleased with him) narrated to me Allah's Messenger (ﷺ) as having said this: Beware, there can be an element of interest in credit.
حَدَّثَنَا الْحَكَمُ بْنُ مُوسَى، حَدَّثَنَا هِقْلٌ، عَنِ الأَوْزَاعِيِّ، قَالَ حَدَّثَنِي عَطَاءُ بْنُ أَبِي، رَبَاحٍ أَنَّ أَبَا سَعِيدٍ الْخُدْرِيَّ، لَقِيَ ابْنَ عَبَّاسٍ فَقَالَ لَهُ أَرَأَيْتَ قَوْلَكَ فِي الصَّرْفِ أَشَيْئًا سَمِعْتَهُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم أَمْ شَيْئًا وَجَدْتَهُ فِي كِتَابِ اللَّهِ عَزَّ وَجَلَّ فَقَالَ ابْنُ عَبَّاسٍ كَلاَّ لاَ أَقُولُ أَمَّا رَسُولُ اللَّهِ صلى الله عليه وسلم فَأَنْتُمْ أَعْلَمُ بِهِ وَأَمَّا كِتَابُ اللَّهِ فَلاَ أَعْلَمُهُ وَلَكِنْ حَدَّثَنِي أُسَامَةُ بْنُ زَيْدٍ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " أَلاَ إِنَّمَا الرِّبَا فِي النَّسِيئَةِ " .
Muslim
The Book of Musaqah • Hadith 130