Revelation 15:6 - Matthew Poole's English Annotations on the Holy Bible

And the seven angels; the seven ministers of God's vengeance on antichrist, to whom the vials were given. Came out of the temple; that is, out of the tabernacle of the testimony; for in Moses's tabernacle there was only this inward court for the priests, the people worshipped without. They came (as the high priest was wont) out of the oracle to bring God's answer to all his saints prayers. Having the seven plagues: the answer was seven plagues, that is, that God had employed them to bring seven plagues successively upon the antichristian party, and all the enemies of his church, till by them they should be consumed. Clothed in pure and white linen, and having their breasts girded with golden girdles; these angels came in the habit of high priests, when they went in to inquire of God, or came out with an answer from God.