Musnad Ahmad 799:69

Abu Mu'awiyah narrated to us, from Hajjaj, from Sa'id ibn 'Ubayd ibn Zayd ibn 'Uqbah, from his father, from Samurah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If a man's property is stolen, or his property is lost, and he finds it in the possession of a specific man, then he is more entitled to it, and the purchaser shall return to the seller for the price."