Narrated Ibn `Abbas
The Prophet (ﷺ) came to Medina and the people used to pay in advance the price of dates to be delivered within two or three years. He said (to them), "Whoever pays in advance the price of a thing to be delivered later should pay it for a specified measure at specified weight for a specified period."
Narrated Ibn `Abbas
The Prophet (ﷺ) came (to Medina) and he told the people (regarding the payment of money in advance that they should pay it) for a known specified measure and a known specified weight and a known specified period.
Narrated Shu`ba
Muhammad or `Abdullah bin Abu Al-Mujalid said, "Abdullah bin Shaddad and Abu Burda differed regarding As-Salam, so they sent me to Ibn Abi `Aufa and I asked him about it. He replied, 'In the lifetime of Allah's Messenger (ﷺ), Abu Bakr and `Umar, we used to pay in advance the prices of wheat, barley, dried grapes and dates to be delivered later. I also asked Ibn Abza and he, too, replied as above.' "