حَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنِ ابْنِ أَبِي نَجِيحٍ، حَدَّثَنِي عَبْدُ اللَّهِ، بْنُ كَثِيرٍ عَنْ أَبِي الْمِنْهَالِ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَدِمَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَالنَّاسُ يُسْلِفُونَ فَقَالَ لَهُمْ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ مَنْ أَسْلَفَ فَلاَ يُسْلِفْ إِلاَّ فِي كَيْلٍ مَعْلُومٍ وَوَزْنٍ مَعْلُومٍ ‏"‏ ‏.‏

Ibn 'Abbas (Allah be pleased with them) reported that when Allah's Messenger (PBUH) came to (Medina) and the people were paying in advance (for the fruits, etc.), he said to them: He who makes an advance payment should not make advance payment except for a specified measure and weight (and for a specified period). Translation Not Available

Book Ref: Sahih Muslim Book 22 Hadith 3907
Web Ref:  Sahih Muslim Book 10 Hadith 1604 b