John Calvin Commentary Isaiah 42:12

"Let them give glory unto Jehovah, and declare his praise in the islands." — Isaiah 42:12 (ASV)

Let them give glory to Jehovah. He explains that the nature of that shouting will be to celebrate the praises of God. This is because his goodness and mercy will be seen everywhere. Therefore, he instructs them to celebrate this redemption with a cheerful voice, because its blessed consequences will be shared by all the nations.

And so, we are reminded to cry aloud in the present day with the greatest earnestness when we proclaim the praises of God, so that we ourselves may be stirred up and, by our example, may stir others to do the same. For it is impossible for those who have truly tasted God's grace to be lukewarm, to mutter, or, as the saying goes, to sing to themselves and to the muses.