Musnad Ahmad 938:82

Yazid narrated to us, Muhammad ibn Ishaq informed us, from Nafi’, from Ibn ‘Umar, from Zayd ibn Thabit: "That the Messenger of Allah (peace and blessings of Allah be upon him) forbade *al-muzabanah* (the sale of fruits on the trees for harvested fruits) and *al-muhaqalah* (the sale of standing crops for harvested grain), except that he granted a concession to the people of *al-‘araya* (the owners of individual date palms) to sell them for the equivalent of their estimated yield."