2 And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit.
[AD 990] Oecumenius on Revelation 9:1-4
Up to now the vision was describing for us the way and the kind of plagues with which the [elements] of earth and heaven, and with them human beings, were being consummated or changed. But now as though the consummation has already come about and the resurrection has been effected, he describes the punishments accorded to sinners.

He says, I saw a star fallen from heaven to earth, meaning that the star is a messenger of God because of its brilliance, which had come down on the earth, where the judgment of sinners will occur, at a certain place which one of the holy prophets named “the valley of Jehoshaphat.”

He says, The key of the shaft of the bottomless pit was given to him. He calls Gehenna a shaft of a bottomless pit. That is why there also came up from the shaft smoke as of abundant fire, which was clearly lurking in the shaft. But the smoke symbolizes not only fire, but also darkness; for the word of the prophet, “The voice of the Lord cutting through a flame of fire,” is interpreted by the saints as though it will cut through the illumination of the fire of Gehenna so that only scorching heat and darkness remain in it.

He says, The sun and the air were darkened with the smoke of the shaft, not because these elements were darkened, but because those who had been thrown into the shaft were filled with darkness because of their punishment, and so were blind to the air and the sun. For this is what one of the holy prophets also said: “The sun” will be darkened “at noon,” describing the disasters of the Jews, not that the sun was darkened, but that they suffered this in their affliction and could not see the sun; for the extent of their disasters was like being overcome with dizziness.

He says, And from the smoke locusts came out on the earth. I think that he calls the worms locusts, about which Isaiah says, “Their worm shall not die, and their fire shall not be quenched,” perhaps calling the biting sting of the soul and its persistent and creeping pain a worm.

He says, And they were given power like the power which scorpions have on earth. They were told not to harm the grass of the earth or any green growth or any tree, but only those human beings who do not have the seal of God upon their foreheads once the earth had been changed and renewed. For it is said somewhere about it, “You will send forth your spirit and they will be created, and you will renew the face of the earth.”

It was no longer a good thing for any adornment of the earth to be struck, neither a tree nor anything growing, except only human beings, and of these only those who do not have the seal of God on their foreheads. For those human beings who are completely holy and pure have received the place mentioned earlier on, being constantly with Christ and in sight of the divine throne. But those who are less holy but nevertheless who have been baptized, and who bear the sign of Christ on their foreheads and who have not been completely rejected, and have not gravely defiled themselves and their baptism by their unnatural deeds, but as it were are midway between good and evil, remain upon earth but escape punishment.

For if this were not so, why would the Lord have said to those who had made good use of the pounds entrusted to them, “Have authority over ten cities,” and to another, “over five cities,” as if they were going to rule over the inferior, while their subjects went altogether unpunished? For who would choose to rule those who were being punished and constantly gnashing their teeth, and bewailing their unspeakable sufferings? I am not of course referring to the saints, nor to people like them, but simply to people deserving our sympathy. Who would choose to rule over them, unless he himself, too, were going to suffer something similar to the incurable condition of those who were being punished?

The third part of human beings is handed over to punishment, since they are sinners and impious and have not received the faith of Christ. That is why it is said that those were struck who had not been sealed with the seal of God.

[AD 390] Ticonius on Revelation 9:2
“He opened the shaft of the pit” means that he revealed his own heart and taught people to sin without any fear or shame. “And smoke arose from the pit,” that is, from the heart of a blasphemous people which also persecutes the church. “And the sun and air were darkened by the smoke of the pit.” The sins that people constantly commit through the world obscure among them the sun of faith and of righteousness and in some produce a blindness so that they do not see the light of truth. “As smoke from a great furnace.” This smoke that precedes the fire of the furnace generally refers to the last persecution, for the earlier persecution burns against the church, and then the crowd of hypocrites and unbelievers will be manifested. And outside [the church] the insanity of many caused by this smoke is already advanced.

[AD 542] Caesarius of Arles on Revelation 9:2
[The devil] revealed his own heart, which sins without any fear or shame. “And smoke rose from the pit,” that is, from a people that covers and obscures the church, so that it is said that “the sun and air were darkened with the smoke.” It says that the sun was darkened, not that it fell to the earth. For the sins of evil and prideful persons, which are constantly being committed throughout the world, obscure the sun, that is, obscure the church and sometimes cause darkness for the saints and the righteous. For the number of the evil is so great that it is often with great difficulty that the good among them become evident.

[AD 735] Bede on Revelation 9:2
And the smoke of the pit arose, like the smoke of a great furnace, etc. Proclaiming the great furnace, that is, the final persecution, the heretical madness rages, not only attempting to obscure the light of the weaker ones, who, like the air, touch the boundaries of the earth and heaven in some way, but also striving to obscure the light of the exalted ones, though not able to extinguish it. For even the elect will be led into error, if possible (Matthew XXIV).

[AD 1171] Jacob Bar-Salibi on Revelation 9:2
'On this Caius objects, that according to this, the unrighteous are consumed by the locusts; whereas Scripture has said that sinners prosper and the righteous are persecuted, in the world' [Ps. lxxiii. 12 ] ; and Paul, that the faithful shall be persecuted and the evil shall flourish, deceiving and being deceived [2 Tim. iii. 12, 13].

But Hippolytus answers him, and says that the faithful, those who are persecuted by the unrighteous, at this period are to have rest, because they have been sealed; but the unrighteous who persecuted the saints, on them comes the plague of locusts; even as the Egyptians were devoured, and the Hebrews were free from the plagues, while they dwelt in one place. Thus the saints in this time are to be in well-being, even as our Lord said, When these things begin to be, be of good cheer, and lift up your heads, inasmuch as your redemption is nigh [St. Luke, xxi. 28]; that is, when plagues come on the evil, the righteous have rest. And this, that evil men deceive and are deceived [2 Tim. iii. 13], at the present day is coming to pass : that crafty men, who alter the words of the Lord and of the Scriptures after their evil thoughts, that even though at the present day they are proceeding further, yet in the end they are to be rebuked : even as Jannes and Jambres, who withstood Moses [ib. 8, 9], and afterwards were overcome and put to shame.'