كتاب البيوع
21  
The Book of Transactions
(14)
Chapter: The prohibition of selling fresh dates in exchange for dry dates except in the case of 'Araya
(14)
باب تَحْرِيمِ بَيْعِ الرُّطَبِ بِالتَّمْرِ إِلاَّ فِي الْعَرَايَا ‏‏
Sahih Muslim 1539 g

Zaid b Thabit (Allah be pleased with him) reported that Allah's Messenger (ﷺ) gave concession in case of al-'ariyya transactions (for exchanging dates) for dates with measure. Yahya said:

'Ariyya implies that a person should buy fresh dates on the tree for his family to eat against a measure of dry dates.
وَحَدَّثَنَا مُحَمَّدُ بْنُ رُمْحِ بْنِ الْمُهَاجِرِ، حَدَّثَنَا اللَّيْثُ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، حَدَّثَنِي زَيْدُ بْنُ ثَابِتٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رَخَّصَ فِي بَيْعِ الْعَرِيَّةِ بِخَرْصِهَا تَمْرًا ‏.‏ قَالَ يَحْيَى الْعَرِيَّةُ أَنْ يَشْتَرِيَ الرَّجُلُ ثَمَرَ النَّخَلاَتِ لِطَعَامِ أَهْلِهِ رُطَبًا بِخَرْصِهَا تَمْرًا ‏.‏
Reference : Sahih Muslim 1539g
In-book reference : Book 21, Hadith 82
USC-MSA web (English) reference : Book 10, Hadith 3683
  (deprecated numbering scheme)