Mustadrak al-Hakim — Hadith 1450

It is narrated from Sayyiduna Thawban (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever leaves behind him a hoarded treasure (kanz: wealth on which zakah was not paid), on the Day of Resurrection it will be made to appear to him as an extremely venomous, bald serpent with two black spots above its eyes. It will pursue his mouth, and the person will say: Woe to you, what are you? It will reply: I am your treasure which you left behind you. It will keep pursuing him until he puts his hand into its mouth and it chews it up; then it will swallow the rest of his body as well."
This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs did not record it. There is also an authentic supporting hadith (shahid) for it that meets his condition: