Musnad Ahmad 27:1038

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Ayyub—meaning al-Sakhtiyani—from Nafi', from Ibn 'Umar, that the Messenger of Allah (ﷺ) said: "Whichever man sells date palms that have been pollinated, then their fruit belongs to their first owner, unless the buyer stipulates [otherwise]."