Isaiah 34:5
For my sword shall be bathed in heaven: behold, it shall come down upon Idumea, and upon the people of my curse, to judgment. For my sword shall be bathed in heaven: behold, it shall come down upon Idumea, and upon the people of my curse, to judgment.
The bathing of the sword in heaven means that divine judgment is imminent and ready to descend. It will come down upon Idumea, identified as the people resting under God's curse, to execute judgment upon them. As that descending judgment draws near, heaven itself is in commotion. Because the time is so urgent, God's messengers must hasten their work.