Revelation 6:9

9 When he opened the fifth seal, I saw under the altar the souls of those who had been slain because of the word of God and the testimony they had maintained.

Read Revelation 6:9 Using Other Translations

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:
When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne.
When the Lamb broke the fifth seal, I saw under the altar the souls of all who had been martyred for the word of God and for being faithful in their testimony.