The Messenger of Allah ﷺ said, "There is no owner of a treasure who fails to pay its zakat except that it will be heated for him in the fire of Hell and forged into plates, with which his sides and forehead will be branded, until Allah judges between His servants on a Day whose length is fifty thousand years. Then he will be shown his path, either to Paradise or to the Fire." The hadith continues.
قال رسول الله ﷺ: ما من صاحب كنز لا يؤدي زكاته إلا أحمي عليه في نار جهنم، فيجعل صفائح، فيكوى بها جنباه وجبينه حتى يحكم الله بين عباده، في يوم كان مقداره خمسين ألف سنة، ثم يرى سبيله، إما إلى الجنة وإما إلى النار… الحديث.
Muslim narrated it in the Book of Zakat (26:987) from Muhammad bin Abdul-Malik Umawi, who said, Abdul-Aziz bin Mukhtar told us, who said, Suhayl bin Abu Salih told us, from his father, from Abu Hurairah, who said, and then he mentioned it.