Salim narrates from his father (Sayyiduna Abdullah bin Umar (may Allah be pleased with them both)) that the Messenger of Allah (peace and blessings be upon him) "forbade selling fruit before it ripens, and also forbade selling fruit for dried dates."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10586