Abu Sa'id (Allah be pleased with him) reported: Dates were brought to Allah's Messenger (ﷺ), and he said: These dates are not like our dates, whereupon a man said: We sold two sa's of our dates (in order to get) one sa', of these (fine dates), whereupon Allah's Messenger (ﷺ) said: That is interest; so return (these dates of fine quality), and get your (inferior dates) ; then sell our dates (for money) and buy for us (with the help of money) such (fine dates).
Source: sunnah.com
Other translations
Arabic
وَحَدَّثَنَا سَلَمَةُ بْنُ شَبِيبٍ، حَدَّثَنَا الْحَسَنُ بْنُ أَعْيَنَ، حَدَّثَنَا مَعْقِلٌ، عَنْ أَبِي قَزَعَةَ، الْبَاهِلِيِّ عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ، قَالَ أُتِيَ رَسُولُ اللَّهِ صلى الله عليه وسلم بِتَمْرٍ فَقَالَ " مَا هَذَا التَّمْرُ مِنْ تَمْرِنَا " . فَقَالَ الرَّجُلُ يَا رَسُولَ اللَّهِ بِعْنَا تَمْرَنَا صَاعَيْنِ بِصَاعٍ مِنْ هَذَا . فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " هَذَا الرِّبَا فَرُدُّوهُ ثُمَّ بِيعُوا تَمْرَنَا وَاشْتَرُوا لَنَا مِنْ هَذَا " .
sunnah.com