Sahih Muslim
The Book of Transactions (Kitab Al-Buyu)
Book Number: 010 / Hadith Number: 3697
Ibn 'Umar (Allah be pleased with them) reported Allah's Messenger (may peace be upon him) having forbidden Muzabana, and Muzabana implies the selling of dry dates for fresh dates on the tree with a definite measure (making it clear) that in case it increases, it belongs to me and if it is less, it is my responsibility.