A.T. Robertson Commentary Revelation 14:9

"And another angel, a third, followed them, saying with a great voice, If any man worshippeth the beast and his image, and receiveth a mark on his forehead, or upon his hand," — Revelation 14:9 (ASV)

A third (τριτος). "The third of this succession of herald angels denounces the Caesarworshippers" (Swete). Cf. 13:12f.. This counter proclamation (verses 9-12) warns those tempted to yield to the threats of the second beast about boycott and death (13:11-17).

If any man worshippeth the beast and his image (ε τις προσκυνε το θηριον κα την εικονα αυτου). Condition of first class challenging those afraid of the beast. Note accusative (θηριον) after προσκυνε, not dative as in verse 7.

And receiveth a mark (κα λαμβανε χαραγμα). Carries on the same condition and picks up the very language of 13:16. These Caesar-are guilty of an "eternal sin" .