(for those who disbelieve in their Lord is the torment of Hell, and worst indeed is that destination.) This means that this will be the worst end and a terrible destiny.
إِذَآ أُلْقُواْ فِيهَا سَمِعُواْ لَهَا شَهِيقًا
(When they are cast therein, they will hear its Shahiq) Ibn Jarir said, "This means the sound of shouting."
وَهِىَ تَفُورُ
(while it is simmering.) Ath-Thawri said, "It will boil them just as a small number of seeds are boiled in a lot of water." Then Allah says,
وَلَقَدْ زَيَّنَّا السَّمَاءَ الدُّنْيَا بِمَصَابِيحَ وَجَعَلْنَاهَا رُجُومًا لِّلشَّيَاطِينِ (And We have decorated the nearest sky with lamps, and have made them devices to stone the devils, and We have prepared for them the punishment of Hell....67:5). The word 'masabih' (translated above as 'lamps' ) stands for 'stars'. The fact that the sky is decorated with stars does not necessarily imply that they should be studded with them inside or under the sky. The decoration is available also to the situation when the stars are far below the sky in space as modern research has proved it by observation. This is not contradictory to the classical interpretation.
A study of the present world reveals a certain contradiction. The whole universe (except for human beings) is running quite perfectly and in the most well-organised manner. It has no defect in it anywhere. On the contrary, one finds many defects in human life. This is because the nature of man’s creation is different. Man in this world is living under testing conditions. A test essentially demands freedom of action. This freedom of action has given the opportunity to human beings to create disturbance and imbalance in the world. The transgression rampant in the human world is the price of human freedom. If such conditions did not exist, how could divine approval be given to those worthy persons who did not transgress, in spite of having opportunities to transgress and who abstained from arrogance in spite of having the power to be arrogant?
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.