(71) باب سَلَفٍ وَبَيْعٍ وَهُوَ أَنْ يَبِيعَ السِّلْعَةَ عَلَى أَنْ يُسْلِفَهُ سَلَفًا
It was narrated from 'Amr bin shu'aib, from his father, from his grandfather, that:
the Messenger of Allah prohibited lending on the condition of a sale, or to have two conditions in one transaction, or to profit from what you do not posses.
Reference: Sunan an-Nasa'i 4629
In-book reference: Book 44, Hadith 181
English translation: Vol. 5, Book 44, Hadith 4633