Allah says to His Messenger Muhammad ﷺ: "Say to the people, `What I have brought to you from your Lord is the truth, in which there is no confusion or doubt."'
فَمَن شَآءَ فَلْيُؤْمِن وَمَن شَآءَ فَلْيَكْفُرْ
(Then whosoever wills, let him believe; and whosoever wills, let him disbelieve.) This is a type of threat and stern warning, after which Allah says,
إِنَّآ أَعْتَدْنَا
(Verily, We have prepared), meaning made ready,
لِّلظَّـلِمِينَ
(for the wrongdoers,) meaning those who disbelieve in Allah, His Messenger and His Book,
نَارًا أَحَاطَ بِهِمْ سُرَادِقُهَا
(a Fire whose walls will be surrounding them.) Ibn Jurayj said that Ibn `Abbas said,
أَحَاطَ بِهِمْ سُرَادِقُهَا
(a Fire whose walls will be surrounding them.) "A wall of fire."
وَإِن يَسْتَغِيثُواْ يُغَاثُواْ بِمَآءٍ كَالْمُهْلِ يَشْوِى الْوجُوهَ
(And if they ask for drink, they will be granted water like Al-Muhl, that will scald their faces.) Ibn `Abbas said; "Al-Muhl is thick water which is similar to the sediment in oil." Mujahid said, "It is like blood and pus." `Ikrimah said, "It is the thing that is heated to the ultimate temperature." Others said: "It is everything that is melted." Qatadah said, "Ibn Mas`ud melted some gold in a grove, and when it became liquid and foam rose to the top, he said, this is the thing that is most like Al-Muhl." Ad-Dahhak said: "The water of Hell is black, and it itself is black and its people are black." There is nothing contradictory in these comments, for Al-Muhl includes all of these unpleasant characteristics, it is black, evil-smelling, thick and hot, as Allah said,
يَشْوِى الْوجُوهَ
(it will scald their faces.) meaning because of its heat. When the disbeliever wants to drink it and brings it close to his face, it will scald it so that the skin of his face falls off into it. Sa`id bin Jubayr said, "When the people of Hell get hungry, they will ask for relief from it, and they will be given the tree of Zaqqum from which they will eat. The tree will tear off the skin of their faces, and if anyone who knew them were to pass by, he would recognize the skin of their faces in the tree. Then they will feel thirsty, so they will ask for drink, and they will be granted water like Al-Muhl, that is what has been heated to the ultimate temperature. When it is brought near their mouths, the flesh of their faces from which the skin has been torn off will be baked." After describing this drink in these horrifying qualities, Allah says:
بِئْسَ الشَّرَابُ
(Terrible is the drink,) meaning, how awful this drink is. Similarly, He says in another Ayah:
وَسُقُواْ مَآءً حَمِيماً فَقَطَّعَ أَمْعَآءَهُمْ
(and be given to drink boiling water so that it cuts up their bowels.) 47:15
تُسْقَى مِنْ عَيْنٍ ءَانِيَةٍ
(They will be given to drink from a boiling spring.) 88:5
وَبَيْنَ حَمِيمٍ ءَانٍ
(They will go between it (Hell) and the fierce boiling water.) 55:44
وَسَآءَتْ مُرْتَفَقًا
(and an evil Murtafaq!) means, how evil a place is the Fire to dwell and rest and gather. As Allah says elsewhere:
إِنَّهَا سَآءَتْ مُسْتَقَرّاً وَمُقَاماً
(Evil indeed it (Hell) is as an abode and as a place to rest in.) 25:66