Musnad Ahmad 30:1066

The Messenger of Allah, peace and blessings of Allah be upon him, said: "The treasure of one of you will be a bald-headed serpent on the Day of Resurrection." He said: "Its owner will flee from it, and it will pursue him and say: 'I am your treasure.'" He said: "By Allah, it will not cease to pursue him until he stretches out his hand, and it will snap it into its mouth."