Enter into the rock - That is, into the “holes or caverns” in the rocks, as a place of refuge and safety; compare Isaiah 2:19, and Revelation 6:15-16. In times of invasion by an enemy, it was natural to flee to the fastnesses or to the caverns of rocks for refuge. This expression is highly figurative and poetic. The prophet warns them to flee from danger. The sense is, that such were their crimes that they would certainly be punished; and he advises them to flee to a place of safety.
And hide thee in the dust - In Isaiah 2:19, this is ‘caves of the dust.’ It is parallel to the former, and probably has a similar meaning. But “may” there not be reference here to the mode prevailing in the East of avoiding the monsoon or poisonous heated wind that passes over the desert? Travelers there, in order to be safe, are obliged to throw themselves down, and to place their mouths close to the earth until it has passed.
For fear of the Lord - Hebrew ‘From the face of the terror of the Lord.’ That is, the punishment which God will inflict will sweep over the land, producing fear and terror.
And for the glory ... - That is, the honor or splendor which will attend him when he comes forth to inflict judgment on the people; Isaiah 2:19-20.