Maliks Muwatta Book 17, Hadith Number 22.

Yahya related to me from Malik from Abdullah ibn Dinar from Abu’s-Salih as-Samman that Abu Hurayra used to say, “Anyone who has wealth on which he has not paid zakat will, on the day of rising, find his wealth made to resemble a white-headed serpent with a sac of venom in each cheek which will seek him out until it has him in its power, saying, ‘I am the wealth that you had hidden away.'”