v1-3: Zophar the dogmatic! His words are harsh, even cruel.
His immediate accusation against Job is of his many words and his idle talk, 'You've said much, but said little.'
v4: He attacks Job's claim of integrity; although Job had not claimed to be pure in God's sight. We must be careful that we do not distort or caricature the opinions or beliefs of others.
v5: Indeed, when God speaks, all are brought to silence.
v6: God does reveal true wisdom.
Zophar's suggestion, here, is that God has punished Job less then he deserves. It is hardly caring to tell him that things could be much worse. No words of comfort here.
v7-9: God's ways are unsearchable; this theme recurs several times in the book. The mysteries of God are unfathomable; higher, deeper, longer, wider; mere human intelligence is utterly incapable of knowing God's ways.
v10: God can do what He likes; we cannot. God is not answerable to anyone.
v11-12: Zophar infers that Job is deceitful and wicked, and that he is being judged by God.
v13-15: The call to repent, repeated by Eliphaz in 22.21-23. Once confession is made, the conscious is clear.
v16-19: The reward of repentance.
v20: The judgment upon the one who will not repent. The wicked are without hope.