Sahih Muslim | Book 10 | Hadith Number 3666

Narrated by Ibn 'Umar (Allah be pleased with them)
Ibn 'Umar (Allah be pleased with them) reported that Allah's Messenger (may peace be upon him) forbade the sale of palm-trees (i.e. their trusts) until the dates began to ripen, and ears of corn until they were white and were safe from blight. He forbade the seller and the buyer.