It was narrated that Abu Al Minhal said: “I heard Ibn ‘Abbas say: ‘When the Prophet صلی اللہ علیہ وآلہ وسلم came (to Al-Madinah), they used to pay in advance for dates, two or three years in advance. He forbade them that and said: ‘Whoever pays in advance for dates, let him pay for a known amount or a known weight, to be delivered at a known time.” (Sahih)