Sahih Bukhari, Chapter: Obligatory Charity Tax (Zakat)

Allah's Apostle said, "Whoever is made wealthy by Allah and does not pay the Zakat of his wealth, then on the Day of Resurrection his wealth will be made like a bald-headed poisonous male snake with two black spots over the eyes. The snake will encircle his neck and bite his cheeks and say, 'I am your wealth, I am your treasure.' " Then the Prophet recited the holy verses:-- 'Let not those who withhold . . .' (to the end of the verse). (3.180).