The sale of date-palms before their benefit is evident Sahih al-Bukhari 2197
Arabic hadith text
حَدَّثَنِي عَلِيُّ بْنُ الْهَيْثَمِ، حَدَّثَنَا مُعَلًّى، حَدَّثَنَا هُشَيْمٌ، أَخْبَرَنَا حُمَيْدٌ، حَدَّثَنَا أَنَسُ بْنُ مَالِكٍ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ نَهَى عَنْبَيْعِ الثَّمَرَةِ حَتَّى يَبْدُوَ صَلاَحُهَا، وَعَنِ النَّخْلِ حَتَّى يَزْهُوَ.قِيلَ وَمَا يَزْهُو قَالَ يَحْمَارُّ أَوْ يَصْفَارُّ
Translation
Narrated Anas bin Malik
The Prophet (ﷺ) forbade the sale of fruits till their benefit is evident; and the sale of date palms till the dates are almost ripe. He was asked what 'are almost ripe' meant. He replied, "Got red and yellow."