The Messenger of Allah ﷺ forbade the sale of date palms until their fruit becomes fit to eat.
حدثنا أزهر بن القاسم الراسبي بمكة وكثير بن هشام قالا حدثنا هشام عن أبي الزبير
نهى رسول الله ﷺ عن بيع النخل حتى يطعم
Its isnad is sahih. Azhar bin Qasim is trustworthy, and the hadith has already appeared at 14794.