Abū Hurairah reported Allah’s Messenger (peace and blessings of Allah be to him) as saying: “If an owner of gold or silver does not pay what is due to him, when the Day of Resurrection would come, plates of fire would be beaten out for him; these would then be heated in the fire of Hell and his sides, his forehead and his back would be cauterised with them. Whenever these cool down, (the process is) repeated during a day, the duration of which would be fifty thousand years, until judgement is pronounced among servants, and he sees whether his path is to take him to Paradise or to Hell.…”
(Muslim)
Zakat is one of the basic requirements of Islamic faith. The Qur’ān as well as the Blessed Messenger has repeatedly exonerated believers to pay Zakat.
If the owner of gold or silver of the specific measure or equivalent cash does not pay Zakat, the Blessed Messenger warns him against unending process of grave punishment. The punishment is cauterising his sides, forehead and back with the plates of fire beaten out and then heated in the fire of Hell. When these plates cool down, the process would be repeated until the judgement is pronounced. It will continue for the whole Day of Judgement, which would be as long as fifty thousand earthly years.
As for the owner of camels, sheep or cattle who fails to pay Zakat, the Messenger added that the animals would trample him with their hoofs and bite him with their mouths, until the judgement is pronounced.