(14) باب تَحْرِيمِ بَيْعِ الرُّطَبِ بِالتَّمْرِ إِلاَّ فِي الْعَرَايَا
Ibn 'Umar (Allah be pleased with them) reported Allah's Messenger (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.
Reference: Sahih Muslim 1542 e
In-book reference: Book 21, Hadith 96
USC-MSA web (English) reference(deprecated numbering scheme): Book 10, Hadith 3697