From Sahih Muslim (Hadith 3873):
Abu Bakhtari reported:I asked Ibn 'Abbas (Allah be pleased with them) about the sale of dates. He said: Allah's Messenger (ﷺ) forbade the sale of dates of the trees until one eats them or they are eaten (i. e. they are fit to be eaten) or until they are weighed (or measured). I said: What does it imply:" Until it is weighed"? Thereupon a person who was with him (Ibn Abbas) said: Until he is able to keep it with him (after plucking them)
Reference: Muslim 3873