Sing... shout. Figure of speech Poeanismos.
break forth into singing. See note on Isaiah 14:7.
Related Commentaries of Isaiah 44:23
Isaiah 44:23
23 Sing, O ye heavens; for the LORD hath done it: shout, ye lower parts of the earth: break forth into singing, ye mountains, O forest, and every tree therein: for the LORD hath redeemed Jacob, and glorified himself in Israel.