Revelation 6:9-11 King James Version (KJV)
9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:
10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?
11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
Revelation 6:9-11 World English Bible (WEB)
9 When he opened the fifth seal, I saw underneath the altar the souls of those who had been killed for the Word of God, and for the testimony of the Lamb which they had. 10 They cried with a loud voice, saying, “How long, Master, the holy and true, until you judge and avenge our blood on those who dwell on the earth?” 11 A long white robe was given to each of them. They were told that they should rest yet for a while, until their fellow servants and their brothers, [a] who would also be killed even as they were, should complete their course.