the Prophet forbade selling fresh dates still on the tree for dried dates. Ibn 'Umar said: "Azid bin Thabit narrated to me, that Messenger of Allah permitted that in the case o 'Ayaya"' (Using translation from Nasāʾī 4532)  

أَنَّ النَّبِيَّ ﷺ نَهَى عَنْ بَيْعِ الثَّمَرِ بِالتَّمْرِ وَقَالَ ابْنُ عُمَرَ حَدَّثَنِي زَيْدُ بْنُ ثَابِتٍ أَنَّ رَسُولَ اللهِ ﷺ رَخَّصَ فِي بَيْعِ الْعَرَايَا  

Ibn 'Umar (Allah be pleased with them) reported Messenger of Allah ﷺ having forbidden Muzabana, and Muzabana implies the selling of dry dates for fresh dates on the tree with a definite measure (making it clear) that in case it increases, it belongs to me and if it is less, it is my responsibility. (Using translation from Muslim 1542e)  

أَنَّ رَسُولَ اللهِ ﷺ نَهَى عنِ الْمُزَابَنَةِ وَالْمُزَابَنَةُ أَنْ يُبَاعَ مَا فِي رُءُوسِ النَّخْلِ بِتَمْرٍ بِكَيْلٍ مُسَمًّى إِنْ زَادَ فَلِي وَإِنْ نَقَصَ فَعَلَيَّ