Musnad Ahmad

It is narrated from Hazrat Abu Hurairah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Whoever does not pay the zakat of his wealth, all his treasures will be made into a slab and heated in the fire of Hell. Then his forehead, sides, and back will be branded with it. This will be the day whose length, according to your reckoning, will be equal to fifty thousand years, until judgment is passed among the people. After that, he will be shown his path. Similarly, the man who owns camels but does not pay their due zakat, all those camels will come on the Day of Resurrection in a healthier state than before, and the ground will be made soft for them. Thus, they will trample him with their hooves. As soon as the last camel passes, the first one will return, until Allah decides among His servants. This will be the day whose length, according to your reckoning, will be equal to fifty thousand years. After that, he will be shown his path to Paradise or Hell. Similarly, the man who owns goats will face the same fate, except that they will gore him with their horns and trample him with their hooves.