It is narrated from Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever sells a date-palm tree to someone after it has been pollinated, then its (current year's) fruit belongs to the seller, unless the buyer stipulates a condition (that he will also take the fruit), then it is permissible."
Hadith Referenceمسند الإمام الشافعي / كتاب البيوع / 1367
Hadith Takhrijاخرجه البخاري، المساقاة، باب الرجل يكون له ممر أو شرب في حائط او في نخل (2379) ومسلم ، البيوع، باب من باع نخلا عليها تمر (1543)۔