Full Sharh — Mishkat al-Masabih 2696
وَعَنْ أَبِي سَعِيدٍ قَالَ: جَاءَ بِلَالٌ إِلَى النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ بِتَمْرٍ بَرْنِيٍّ فَقَالَ لَهُ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مِنْ أَيْنَ هَذَا؟» قَالَ: كَانَ عِنْدَنَا تَمْرٌ رَدِيءٌ فَبِعْتُ مِنْهُ صَاعَيْنِ بِصَاعٍ فَقَالَ: «أَوَّهْ عَيْنُ الرِّبَا عَيْنُ الرِّبَا لَا تَفْعَلْ وَلَكِنْ إِذَا أَرَدْتَ أَنْ تَشْتَرِيَ فَبِعِ التَّمرَ ببَيْعٍ آخر ثمَّ اشْتَرِ بِهِ»
English Translation
Abu Sa'id said that Bilal brought the Prophet some barni* dates, and when he asked him where he had got them he replied, "I had some inferior dates, so I sold two sa's of them for a sa." He said, "Ah, the very essence of usury, the very essence of usury. Do not do so, but when you wish to buy, sell the dates in a separate transaction, then buy with what you get." (Bukhari and Muslim.) * A type of dates of the best quality, sweet and luscious, red tinged with yellow.
Source
Mishkat al-Masabih(مشكاة المصابيح)
Business Transactions
Hadith Number
2696