(18) باب بَيْعِ الطَّعَامِ مِثْلاً بِمِثْلٍ
Abu Sa'id (Allah be pleased with him) reported:
Dates were brought to Allah's Messenger (ﷺ), and he said: These dates are not like our dates, whereupon a man said: We sold two sa's of our dates (in order to get) one sa', of these (fine dates), whereupon Allah's Messenger (ﷺ) said: That is interest; so return (these dates of fine quality), and get your (inferior dates) ; then sell our dates (for money) and buy for us (with the help of money) such (fine dates).
Reference: Sahih Muslim 1594 b
In-book reference: Book 22, Hadith 123
USC-MSA web (English) reference(deprecated numbering scheme): Book 10, Hadith 3872