Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) "forbade muzabanah and muhaqalah." Muzabanah is selling the fresh fruit of the date palm for dried dates, and muhaqalah is renting out land.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10642