Enter into the rock, and hide thee in the dust, for fear of the LORD, and for the glory of his majesty.
Enter into the rock - poetical form of expressing that, such were their sins they would be obliged by God's judgments to seek a hiding-place from his wrath (Revelation 6:15-16).
Hide thee in the dust - in "caves of the earth" (Hebrew, dust).
For fear of the Lord - literally, from the face of the terror of the Lord.