Jamieson, Fausset & Brown

But when Herod was dead--Miserable Herod! Thou thoughtest thyself safe from a dreaded Rival; but it was He only that was safe from thee; and thou hast not long enjoyed even this fancied security. See on Mat 2:15. behold, an angel of the Lord appeareth in a dream to Joseph in Egypt--Our translators, somewhat capriciously, render the same expression "the angel of the Lord," Mat 1:20; Mat 2:13; and "an angel of the Lord," as here. As the same angel appears to have been employed on all these high occasions--and most likely he to whom in Luke is given the name of "Gabriel," Luk 1:19, Luk 1:26 --perhaps it should in every instance except the first, be rendered "the angel."