(11) Business Transactions
كتاب البيوع
(7a) Chapter: Payment in Advance and Pledge - Section 1
(7) باب السلم والرهن - الفصل الأول
Mishkat al-Masabih 2883 
Ibn 'Abbas said that when God’s Messenger came to Medina they were paying one, two and three years in advance for fruits, so he said, “Those who pay in advance for anything must do so for a specified measure and weight with a specified time fixed.” (Bukhari and Muslim.)
عَنِ ابْنِ عَبَّاسٍ قَالَ: قَدِمَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ الْمَدِينَةَ وَهُمْ يُسْلِفُونَ فِي الثِّمَارِ السَّنَةَ وَالسَّنَتَيْنِ وَالثَّلَاثِ فَقَالَ: «مَنْ سلف فِي شَيْءٍ فَلْيُسْلِفْ فِي كَيْلٍ مَعْلُومٍ وَوَزْنٍ مَعْلُوم إِلَى أجل مَعْلُوم»
 مُتَّفق عَلَيْهِ  (الألباني)حكم :
Reference : Mishkat al-Masabih 2883
In-book reference : Book 11, Hadith 121