What is the ruling on selling crops before they are ripe, in exchange for sheep to be delivered later?

It is not permissible to sell crops before they have ripened, whether the sale is for cash or in kind, immediate or deferred, unless it is stipulated that they be cut immediately for someone who can benefit from them before they ripen. This is due to the Prophet's (peace and blessings be upon him) prohibition of selling corn ears until they turn white and are safe from blight. If the crops are sold on the condition of immediate cutting, then there is no objection to the price being a flock of sheep, described and owed, to be delivered after a known period.