Mujahid bin Jabir مجاهد بن جبر · The Book of Financial Transactions

"The Messenger of Allah said: '(Exchanging) gold for silver is Riba unless it is done on the spot. (Exchanging) dates for dates is Riba unless it is done on the spot. (Exchanging) wheat for wheat is Riba unless it is done on the spot. (Exchanging) barley is Riba unless it is done on the spot."'

"Any man who pollinates a date-palm tree then sells it, the fruits of the tree are for the one who pollinated it, unless the purchaser stipulated otherwise."