It is narrated from Sayyiduna Sahl bin Abi Hathmah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade selling dates for dates, but permitted, regarding 'araya (dates still on the palms), that they be sold according to their estimated amount, so that their owners could eat them fresh.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5612