Yahya related to me from Malik that he had heard that Umar ibnal-Khattab said, "There is no hoarding in our market, and men who haveexcess gold in their hands should not buy up one of Allah's provisionswhich he has sent to our courtyard and then hoard it up against us.Someone who brings imported goods through great fatigue to himself inthe summer and winter, that person is the guest of Umar. Let him sellwhat Allah wills and keep what Allah wills."
USC-MSA web (English) reference: Book 31, Hadith 56
Arabic reference: Book 31, Hadith 1348