Do not sell fresh fruits on the trees until their good condition becomes manifest, and do not sell fresh dates on the trees against dry dates. Salim said: Abdullah informed me on the authority of Zaid b. Thabit, Allah's Messenger (ﷺ) having given concession afterwards in case of ariyya transactions by which dry dates can be exchanged with fresh dates, but he did not permit it in other cases.
Sahih Muslim Book 21, Hadith 77