Sunan Ibn Majah 2256
It was narrated that Abu Sa’eed said:
“The Prophet used to give us dates from the collection (mixed) [1]  dates, and we would exchange them for dates that were better, and we add to the price. [2] The Messenger of Allah said: ‘It is not right to give one Sa of dates for two Sa, nor one Dirham for two Dirham. A Dirham for a Dirham and a Dinar for a Dinar is allowed: the only difference between them is in weight (i.e., the weight must be equal.)’” Sahih
حَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا عَبْدَةُ بْنُ سُلَيْمَانَ، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي سَعِيدٍ، قَالَ كَانَ النَّبِيُّ ـ صلى الله عليه وسلم ـ يَرْزُقُنَا تَمْرًا مِنْ تَمْرِ الْجَمْعِ فَنَسْتَبْدِلُ بِهِ تَمْرًا هُوَ أَطْيَبُ مِنْهُ وَنَزِيدُ فِي السِّعْرِ فَقَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏
"‏ لاَ يَصْلُحُ صَاعُ تَمْرٍ بِصَاعَيْنِ وَلاَ دِرْهَمٌ بِدِرْهَمَيْنِ وَالدِّرْهَمُ بِالدِّرْهَمِ وَالدِّينَارُ بِالدِّينَارِ لاَ فَضْلَ بَيْنَهُمَا إِلاَّ وَزْنًا ‏"‏ ‏.‏