Rent — A metaphor taken from men, that when they would resolutely help one in distress, break and fling open doors and whatever may hinder. Flow down — That all impediments might be removed out of the way: possibly an allusion to God's coming down upon mount Sinai, in those terrible flames of fire.
Related Commentaries of Isaiah 64:1
Isaiah 64:1
1 Oh that thou wouldest rend the heavens, that thou wouldest come down, that the mountains might flow down at thy presence,