isaiah 40:9 O Zion, that bringest good tidings, get thee up into the high mountain; O Jerusalem, that bringest good tidings, lift up thy voice with strength; lift it up, be not afraid; say unto the cities of Judah, Behold your God! - Free Bible Online

      9. Rather, "Oh, thou that bringest good things to Zion; thou that bringest good tidings to Jerusalem." "Thou" is thus the collective personification of the messengers who announce God's gracious purpose to Zion (see on Isa 40:1); Isa 52:7 confirms this [Vulgate and GESENIUS]. If English Version be retained, the sense will be the glad message was first to be proclaimed to Jerusalem, and then from it as the center to all "Judea, Samaria, and the uttermost parts of the earth" (Lu 24:47, 49; Ac 1:8) [VITRINGA and HENGSTENBERG].
      mountain--It was customary for those who were about to promulgate any great thing, to ascend a hill from which they could be seen and heard by all (Jud 9:7; Mt 5:1).
      be not afraid--to announce to the exiles that their coming return home is attended with danger in the midst of the Babylonians. The gospel minister must "open his mouth boldly" (Pr 29:25; Eph 6:19).
      Behold--especially at His second coming (Zec 12:10; 14:5).

JFB.