Musnad Ahmad 30:2799

Rawh ibn ‘Ubadah narrated to us, Shu‘bah narrated to us, Sayyar narrated to us, from al-Sha‘bi, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Do not trade by throwing pebbles, do not engage in Najash (bidding up the price without the intention to buy), and do not trade by al-Mulamasah (touching the garment without examining it). And whoever among you buys a Musarrat (an animal whose milk has been withheld in the udder to deceive the buyer) and dislikes it, let him return it, and let him return with it a Sa‘ of food."