Kal Muhl, the Prophet (s.a.w) said: "Like boiling oil, such that whenever it is brought near him the skin of his face falls into it." And also with this chain, from the is Prophet SAW, that he said: "If a bucket of Ghassaq were poured out in the world, the people of the world would rot. (Da'if) And the meaning of his statement: "The Kithaf of each wall" is its thickness.
Jami` at-Tirmidhi Book 39, Hadith 12
← Previous Hadith "He will be given water of Sadid to drink, he will swallow it..." that the Prophet (s.a.w) said: " It will be brought toward his mouth and he will dislike it, so whenever it is brought closer to him it will melt his face and the skin of his head will fall into it. Then whenever he drinks from it, his bowels will be severed until it comes out from his anus. Allah, the Blessed and Exalted says: "And they will be given water of Hamim to drink such that it cuts up their bowels..." and He says: "And if they call for drink they will be given water of Muhl which melts the faces, the worst of drinks..."

Jami` at-Tirmidhi Book 39, Hadith 11 Next Hadith → Have the Taqwa of Allah as His due, and do not die except as Muslims. And the Messenger of Allah (s.a.w) said: "If only a drop of Az-Zaqqum were to drip into the abode of the world, it would spoil the peoples' livelihood, so how about the person for whom it is his food?"

Jami` at-Tirmidhi Book 39, Hadith 13