Messenger of Allah ﷺ appointed somebody as a governor of Khaibar. That governor brought to him an excellent kind of dates (from Khaibar). The Prophet ﷺ asked, "Are all the dates of Khaibar like this?" He replied, "By Allah, no, O Messenger of Allah ﷺ! But we barter one Sa of this (type of dates) for two Sas of dates of ours and two Sas of it for three of ours." Messenger of Allah ﷺ said, "Do not do so (as that is a kind of usury) but sell the mixed dates (of inferior quality) for money, and then buy good dates with that money."  

أَنَّ رَسُولَ اللَّهِ ﷺ اسْتَعْمَلَ رَجُلاً عَلَى خَيْبَرَ فَجَاءَهُ بِتَمْرٍ جَنِيبٍ فَقَالَ رَسُولُ اللَّهِ ﷺ أَكُلُّ تَمْرِ خَيْبَرَ هَكَذَا قَالَ لاَ وَاللَّهِ يَا رَسُولَ اللَّهِ إِنَّا لَنَأْخُذُ الصَّاعَ مِنْ هَذَا بِالصَّاعَيْنِ وَالصَّاعَيْنِ بِالثَّلاَثَةِ فَقَالَ رَسُولُ اللَّهِ ﷺ لاَ تَفْعَلْ بِعِ الْجَمْعَ بِالدَّرَاهِمِ ثُمَّ ابْتَعْ بِالدَّرَاهِمِ جَنِيبًا  

Once Bilal brought Barni (i.e. a kind of dates) to the Prophet ﷺ and the Prophet ﷺ asked him, "From where have you brought these?" Bilal replied, "I had some inferior type of dates and exchanged two Sas of it for one Sa of Barni dates in order to give it to the Prophet; to eat." Thereupon the Prophet ﷺ said, "Beware! Beware! This is definitely Riba (usury)! This is definitely Riba (Usury)! Don't do so, but if you want to buy (a superior kind of dates) sell the inferior dates for money and then buy the superior kind of dates with that money."  

أَنَّهُ سَمِعَ أَبَا سَعِيدٍ الْخُدْرِيَّ ؓ قَالَ جَاءَ بِلاَلٌ إِلَى النَّبِيِّ ﷺ بِتَمْرٍ بَرْنِيٍّ فَقَالَ لَهُ النَّبِيُّ ﷺ مِنْ أَيْنَ هَذَا قَالَ بِلاَلٌ كَانَ عِنْدَنَا تَمْرٌ رَدِيٌّ فَبِعْتُ مِنْهُ صَاعَيْنِ بِصَاعٍ لِنُطْعِمَ النَّبِيَّ ﷺ فَقَالَ النَّبِيُّ ﷺ عِنْدَ ذَلِكَ أَوَّهْ أَوَّهْ عَيْنُ الرِّبَا عَيْنُ الرِّبَا لاَ تَفْعَلْ وَلَكِنْ إِذَا أَرَدْتَ أَنْ تَشْتَرِيَ فَبِعِ التَّمْرَ بِبَيْعٍ آخَرَ ثُمَّ اشْتَرِهِ  

We used to be given mixed dates (from the booty) and used to sell (barter) two Sas of those dates) for one Sa (of good dates). The Prophet ﷺ said (to us), "No (bartering of) two Sas for one Sa nor two Dirhams for one Dirham is permissible", (as that is a kind of usury). (See Hadith No. 405).  

كُنَّا نُرْزَقُ تَمْرَ الْجَمْعِ وَهْوَ الْخِلْطُ مِنَ التَّمْرِ وَكُنَّا نَبِيعُ صَاعَيْنِ بِصَاعٍ فَقَالَ النَّبِيُّ ﷺ لاَ صَاعَيْنِ بِصَاعٍ وَلاَ دِرْهَمَيْنِ بِدِرْهَمٍ  

I heard Abu Saʿid Al-Khudri saying, "The selling of a Dinar for a Dinar, and a Dirham for a Dirham (is permissible)." I said to him, "Ibn ʿAbbas does not say the same." Abu Saʿid replied, "I asked Ibn ʿAbbas whether he had heard it from the Prophet ﷺ s or seen it in the Holy Book. Ibn ʿAbbas replied, "I do not claim that, and you know Messenger of Allah ﷺ better than I, but Usama informed me that the Prophet had said, 'There is no Riba (in money exchange) except when it is not done from hand to hand (i.e. when there is delay in payment).' "  

أَبُو سَعِيدٍ سَأَلْتُهُ فَقُلْتُ سَمِعْتَهُ مِنَ النَّبِيِّ ﷺ أَوْ وَجَدْتَهُ فِي كِتَابِ اللَّهِ قَالَ كُلُّ ذَلِكَ لاَ أَقُولُ وَأَنْتُمْ أَعْلَمُ بِرَسُولِ اللَّهِ ﷺ مِنِّي وَلَكِنَّنِي أَخْبَرَنِي أُسَامَةُ أَنَّ النَّبِيَّ ﷺ قَالَ لاَ رِبًا إِلاَّ فِي النَّسِيئَةِ