From Sahih Muslim (Hadith 4085):
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: Muslim 4085