Albert Barnes Commentary Revelation 19:14

"And the armies which are in heaven followed him upon white horses, clothed in fine linen, white [and] pure." — Revelation 19:14 (ASV)

And the armies which were in heaven followed him. The heavenly hosts; particularly, it would seem, the redeemed, as there would be some incongruity in representing the angels as riding in this manner. Undoubtedly, the original of this picture is Isaiah 63:3: I have trodden the winepress alone, and of the people there was none with me. These hosts of the redeemed on white horses accompany him to be witnesses of his victory and to participate in the joy of the triumph, not to engage in the work of blood.

Upon white horses. Emblems of triumph or victory. (See Barnes on Revelation 6:2).

Clothed in fine linen, white and clean. The usual garments of those who are in heaven, as everywhere represented in this book. See Revelation 3:4-5; Revelation 4:4; Revelation 7:9, 13; Revelation 15:6.