Tafsir of Al-Anbiya' 21:100

It is the sound of the distressed person’s breath exiting from the deepest part of the chest. The root of al-zafr—as Al-Raghib stated—is the intake of breath such that the ribs expand from it.

It is apparent that the pronoun in “for them” (lahum) applies to all: meaning the worshippers and the worshipped. There is an inclusion here of the rational beings over the non-rational (the idols), as the pronoun for rational beings is used in reference to all, and the same is done in “they will abide” (khalidun). Likewise, those who are capable of exhaling—those possessing life—are given precedence over the idols, as the act of exhaling is attributed to everyone. It is also possible that God Almighty may grant life to the idols that were worshipped, making their state identical to those with them, thus possessing what they possess, which would negate the need for the inclusion of one group over another.

It has been said: The pronoun belongs specifically to those addressed in “Indeed, you” (innakum), by way of transition (iltifat), so there is no need at all to argue for the inclusion of others. This has been refuted on the grounds that it necessitates a discord in the noble arrangement of the text. Do you not see the Almighty’s saying: “You are coming to it” (antum laha waridun), how He grouped them together, prioritizing the addressed? If “for them therein is a sighing” were restricted, it would necessitate a disconnect. The same reasoning applies to His saying: “And they therein will not hear.”

That is, they will not hear one another’s sighing due to the intensity of the horror and the dreadfulness of the torment, according to one interpretation. It is also said: They will not hear even if they were called out to, due to the intensity of their own sighing. Another view is: They will not hear anything that pleases them of speech, as they are not spoken to except with what they detest. It is further said: They are afflicted with literal deafness, based on the apparent meaning of the Almighty’s saying: “And We shall gather them on the Day of Resurrection, fallen on their faces—blind, dumb, and deaf.” This view is as you see it.

The wisdom behind admitting the polytheists into the Fire with their deities is mentioned as being an increase in their distress by seeing them being tormented just as they are, whereas they had once hoped for their intercession. It is also said: The increase in their distress comes from seeing them with them, being the very cause of their torment. It has been said: "Enduring harm while seeing its perpetrator is a nourishment by which bodies wither."

The manifest meaning of some reports is that the final state of those who abide therein is that they do not see one another. Ibn Jarir and a group have narrated from Ibn Mas’ud that he said: "When those who are to abide in the Fire remain, they will be placed in coffins of iron containing nails of iron, then those coffins will be placed in [others of] iron, and they will be cast into the lowest part of Hell. None of them will perceive that anyone else is being tormented in the Fire except himself." Then he recited the verse: “For them therein is a sighing, and they therein will not hear.” From this, another interpretation of “they will not hear” is known. And God Almighty knows best.