Revelation 16:7

And I heard the altar saying, Even so, Lord God Almighty! true and righteous are thy judgments.

Revelation 6:9

And when he had opened the fifth seal, I saw under the altar the souls of them that were slain on account of the word of God, and on account of the testimony which they had borne;

Revelation 19:2

for true and righteous are his judgments; for he hath judged the great harlot, who corrupted the earth with her fornication, and hath avenged the blood of his servants at her hand.

Revelation 14:18

And another angel came out from the altar, who had power over fire; and he cried with a loud cry to him who had the sharp sickle, saying, Thrust in thy sharp sickle, and gather the clusters of the vine of the earth, for the grapes of the earth are fully ripe.

Revelation 8:3-5

And another angel came, and stood at the altar, having a golden censer; and there was given to him much incense, that he should offer it with the prayers of all the saints upon the golden altar which was before the throne.

Revelation 13:10

If any one [leadeth] into captivity he shall go into captivity; if any one shall kill with the sword, he must be killed with the sword. Here is the endurance and the faith of the saints.

Revelation 14:10

the same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation, and he shall be tormented with fire and brimstone in the presence of the angels, and in the presence of the Lamb.

Revelation 15:3-4

And they sing the song of Moses the servant of God, and the song of the Lamb, saying: Great and marvelous are thy works, Lord God Almighty; just and true are thy ways, thou King of the nations;

Treasury of Scripture Knowledge

Summary

And I heard another out of the altar say, Even so, Lord God Almighty, true and righteous are thy judgments.

Bible References

Out

Revelation 6:9
And when he had opened the fifth seal, I saw under the altar the souls of them that were slain on account of the word of God, and on account of the testimony which they had borne;
Revelation 8:3
And another angel came, and stood at the altar, having a golden censer; and there was given to him much incense, that he should offer it with the prayers of all the saints upon the golden altar which was before the throne.
Revelation 14:18
And another angel came out from the altar, who had power over fire; and he cried with a loud cry to him who had the sharp sickle, saying, Thrust in thy sharp sickle, and gather the clusters of the vine of the earth, for the grapes of the earth are fully ripe.

Even

Revelation 15:3
And they sing the song of Moses the servant of God, and the song of the Lamb, saying: Great and marvelous are thy works, Lord God Almighty; just and true are thy ways, thou King of the nations;

True

Revelation 13:10
If any one [leadeth] into captivity he shall go into captivity; if any one shall kill with the sword, he must be killed with the sword. Here is the endurance and the faith of the saints.
Revelation 14:10
the same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation, and he shall be tormented with fire and brimstone in the presence of the angels, and in the presence of the Lamb.
Revelation 19:2
for true and righteous are his judgments; for he hath judged the great harlot, who corrupted the earth with her fornication, and hath avenged the blood of his servants at her hand.