Musnad Ahmad 30:1816

Muhammad ibn Idris narrated to us, Malik informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurairah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Let none of you sell over the sale of another, and let no resident sell for a bedouin, and do not practice najash (bidding up the price without the intention to buy), and do not meet the goods (before they reach the market)."