When Yahweh urges Israel to “go forth from Babylon” and “flee from the Chaldeans,” He also exhorts them sing and shout (Isaiah 48:20).
The songs of deliverance are not merely expressions of joy, though they are obviously that. They are also declarations of Yahweh’s redemption. The text uses three verbs to describe what the singing is to accomplish: By singing, Israel is to announce ( nagad ), “cause to hear” (hiphil of shama ), and “cause to go forth” (hiphil of yatza’ ). The message announced, heard, going forther is “Yahweh has redeemed His servant Jacob.”
Singing declares God’s acts. Song is evangelism.