Sahih Muslim
The Book of Transactions (Kitab Al-Buyu)
Book Number: 010 / Hadith Number: 3666
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 trults) 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.