Ismail Shaybani says: I sold the fruit growing on date trees for one hundred wasq and said: If it turns out to be more, it will be theirs, and if it turns out to be less, it will also be theirs. Then I asked Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) about this, and he said: The Messenger of Allah (peace and blessings be upon him) forbade such a transaction, except that he permitted the sale of ‘ariyah.