The Prophet ﷺ said, "Do not sell fruit until its ripeness becomes apparent."
حدثنا يحيى عن يحيى يعني ابن سعيد عن نافع
عن النبي ﷺ قال لا تتبايعوا الثمر حتى يبدو صلاحه
Its isnad is sahih. Yahya, Ahmad's teacher, is Ibn Saeed Qattan. And his teacher Yahya bin Saeed is al-Ansari. The hadith is a repeat of 5134.