Under the altar (upokatw tou qusiasthriou). "Under" (upokatw), for the blood of the sacrifices was poured at the bottom of the altar ( Leviticus 4:7 ). The altar of sacrifice ( Exodus 39:39 ; Exodus 40:29 ), not of incense. The imagery, as in Hebrews, is from the tabernacle. For the word see Matthew 5:23 , often in Rev. ( Revelation 8:3Revelation 8:5 ; Revelation 9:13 ; Revelation 11:1 ; Revelation 14:18 ; Revelation 16:7 ). This altar in heaven is symbolic, of course, the antitype for the tabernacle altar ( Hebrews 8:5 ). The Lamb was slain ( Rev 5:6Rev 5:9Rev 5:12 ) and these martyrs have followed the example of their Lord. The souls (ta psuca). The lives, for the life is in the blood ( Leviticus 17:11 ), were given for Christ ( Philippians 2:17 ; 2 Timothy 4:6 ). Of the slain (twn espagmenwn). See Revelation 5:6 . Christians were slain during the Neronian persecution and now again under Domitian. A long line of martyrs has followed. For the word of God (dia ton logon tou qeou). As in Revelation 1:9 , the confession of loyalty to Christ as opposed to emperor-worship. And for the testimony which they held (kai dia thn marturian hn eicon). See also Revelation 1:9 . Probably kai equals "even" here, explaining the preceding. The imperfect tense eicon suits the repetition of the witness to Christ and the consequent death.