Narrated Abu Al-Bakhtari:I asked Ibn `Umar about Salam (the fruits of) date-palms. He replied, "The Prophet (ﷺ) forbade the sale of dates till their benefit becomes evident and fit for eating and also the sale of silver (for gold) on credit." I asked Ibn `Abbas about Salam for dates and he replied, "The Prophet (ﷺ) forbade the sale of dates till they were fit for eating and could be estimated
Hadith No. 2248
Sahih al Bukhari