(4) باب السَّلَمِ فِي النَّخْلِ
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."
Reference: Sahih al-Bukhari 2247, 2248
In-book reference: Book 35, Hadith 10
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 35, Hadith 451