The elder is not asking for information. His own answer a moment later shows he already knows (Revelation 7:14). Gill says he spoke "not as being ignorant of them" but "to stir up John to take more notice of them." Barnes notes that in the Bible "answered" can open a speech when no one has spoken, as a reply "to something that is passing through the mind of another." Barnes reads it that way here: John "was looking on the host, and reflecting on the state of things," and the elder answered "the train of thought passing through his mind." Barnes thinks the elder "would seem" to have turned John's eyes to one part of the vast crowd, and he sees a fitness in pointing John to the martyrs at a time of persecution. The first question asks who they are. The second asks where they have come from, and that is where the answer will begin.

John does not guess. He says, "Sir, thou knowest" (Revelation 7:14). The elder then answers both questions himself: "These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb." He goes on to tell where they are now and what awaits them. They are "before the throne of God, and serve him day and night in his temple" (Revelation 7:15). They "shall hunger no more, neither thirst any more," because the Lamb "shall feed them," and "God shall wipe away all tears from their eyes" (Revelation 7:16-17).

The elders first appear seated on four and twenty thrones around God's throne, dressed in white with crowns of gold (Revelation 4:4). Barnes understands them as representatives of the church before the throne. Earlier, white robes were given to the souls of the martyrs under the altar (Revelation 6:9-11).

John calls the elder "Sir," the Greek kyrie, which Barnes explains as a respectful way of addressing someone above you. The Greek behind "great tribulation" reads literally "the tribulation, the great" (tes thlipseos tes megales) in both the Textus Receptus and modern Greek texts. Thlipsis means affliction. Barnes says, "The sense, however, would be better expressed by the phrase great trials." Barnes also describes the palms in their hands as symbols of triumph (Revelation 7:9).

The chapter before this one ends with a frightening question: "who shall be able to stand?" (Revelation 6:17). Revelation 7 then shows a countless multitude standing "before the throne, and before the Lamb" (Revelation 7:9). The elder's question draws John's attention to them so that he can hear their story: they came through great trouble, and they were made clean by the Lamb. Matthew Henry's Concise Commentary puts it this way: "It is not the blood of the martyrs, but the blood of the Lamb, that can wash away sin." Their suffering is real, but it is not what saved them.

Commentators differ on who exactly this crowd is, and it shapes how the scene is read. Barnes sees the multitude as all the redeemed in heaven, with the elder's question seeming to point especially to those who suffered persecution. Gill takes the company as all of God's elect and says the great tribulation "is not to be restrained to any particular time of trouble." Either way, the answer ends in the same place: God dwelling among His people and wiping away their tears (Revelation 7:15, 17).