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 c

Zaid b. Thabit (Allah be pleased with him) reported Allah's Messenger (may peace he upon him) having given concession in case of 'ariyya for selling dry dates (with) fresh dates after measuring them out.

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنْ زَيْدِ، بْنِ ثَابِتٍ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رَخَّصَ لِصَاحِبِ الْعَرِيَّةِ أَنْ يَبِيعَهَا بِخَرْصِهَا مِنَ التَّمْرِ ‏.‏
Reference : Sahih Muslim 1539c
In-book reference : Book 21, Hadith 78
USC-MSA web (English) reference : Book 10, Hadith 3679
  (deprecated numbering scheme)