Isaiah 14:3
And it shall come to pass in the day that the LORD shall give thee rest from thy sorrow, and from thy fear, and from the hard bondage wherein thou wast made to serve, And it shall come to pass in the day that the LORD shall give thee rest from thy sorrow, and from thy fear, and from the hard bondage wherein thou wast made to serve,
The day the Lord gives relief will bring His people rest from sorrow and fear and trouble and from the hard, oppressive bondage and service under which they were made to serve. That rest comes when Satan is bound and held captive, and its arrival brings gladness and rejoicing. The proverb or taunt against the king of Babylon that follows is aimed at Satan himself and celebrates the overthrow and end of the oppressor and his rule.