(18) باب بَيْعِ الطَّعَامِ مِثْلاً بِمِثْلٍ
Abu Sa'id (Allah be pleased with him) reported:
We were given to eat, during the lifetime of Allah's Messenger (ﷺ), dates of different qualities mixed together, and we used to sell two sa's of these for one sa, (of fine quality of dates). This reached Allah's Messenger (ﷺ), whereupon he said: There should be no exchange of two sa's of (inferior) dates for one sa (of fine dates) and two sa's of (inferior) wheat for one sa' of (fine) wheat. and one dirham for two dirharms.
Reference: Sahih Muslim 1595
In-book reference: Book 22, Hadith 124
USC-MSA web (English) reference(deprecated numbering scheme): Book 10, Hadith 3873