Sayyiduna Abu Sa'id al-Khudri and Sayyiduna Abu Hurayrah (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) appointed a man as governor over Khaybar. He came with dates of a fine variety, and he (peace and blessings be upon him) asked: "Are all the dates of Khaybar like this?" He said: By Allah, no, O Messenger of Allah! Rather, we take one sa' of these for two sa', and two sa' for three. The Messenger of Allah (peace and blessings be upon him) said: "Do not do that. Sell the inferior dates for dirhams, then buy fine dates with the dirhams."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10543