A.T. Robertson Commentary Revelation 19:10

"And I fell down before his feet to worship him. And he saith unto me, See thou do it not: I am a fellow-servant with thee and with thy brethren that hold the testimony of Jesus: worship God; for the testimony of Jesus is the spirit of prophecy." — Revelation 19:10 (ASV)

To worship him (προσκυνησα αυτω). First aorist active infinitive of purpose. John either felt that the angel represented God or he was beside himself with excitement over the glorious consummation. He was tempted to worship an angel (Colossians 2:18).

See thou do it not (ορα μη). Repeated in 22:9. Here there is no verb after μη (ellipse of ποιησηις τουτο) as in Mr 1:44; 1 Thessalonians 5:15), the aorist subjunctive of negative purpose with μη after ορα (present active imperative of οραω), a common enough idiom.

Fellow-servant (συνδουλος). The angel refuses worship from John on this ground. All Christians are συνδουλο (fellow-servants) as Christ taught (Matthew 18:28ff.; 24:49) and as Paul (Colossians 1:7; Colossians 4:7) and John (Revelation 6:11) taught. Angels are God's servants also (Hebrews 1:4–14). For "the testimony of Jesus see 1:2,9; 6:9; 12:17; 22:4.

Worship God (τω θεω προσκυνησον). And Christ, who is the Son of God (5:13f.).

The spirit of prophecy (το πνευμα της προφητειας). Explanatory use of γαρ (for) here as in 8. The possession of the prophetic spirit shows itself in witness to Jesus. In illustration see Mr 1:10; Matthew 3:16; Luke 3:21; John 1:51; Revelation 4:1; 10:1; 11:19; 14:17; 15:5; 18:1; 19:1,7-9.