Musnad Ahmad 30:3455

Yazid narrated to us, Hisham informed us, and Muhammad ibn Ja'far said: Hisham narrated to us, from Muhammad, from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him, who said: "Whoever buys a *musarrah* (an animal whose milk has been withheld in the udder to deceive the buyer), he has the choice for three days. If he returns it, he shall return with it a *sa'* of dates, not wheat."