For then shalt thou lift up thy face without spot - That is, thy face shall be bright, clear, and cheerful. Thus, we speak of a bright and happy countenance. Zophar undoubtedly designs to show what his appearance would be, contrasted with what it then was. Now his countenance was dejected and sad. It was disfigured by tears, and terror, and long continued anguish. But if he would put away iniquity, and return to God, his face would be cheerful again, and he would be a happy man.
Yea, thou shalt be steadfast, and shalt not fear - The word rendered "steadfast" (מצק mutsaq) is from יצק yâtsaq, to pour, to pour out, and is applied to liquids, or to metals which are fused and poured into a mould, and which then become hard. Hence, it is used in the sense of firm, solid, intrepid. "Gesenius." Schultens supposes that the reference here is to metallic mirrors, made by casting, and then polished, and that the idea is, that his face would shine like such a mirror. But it may be doubted whether this interpretation is not too refined. The other and more common explanation well suits the sense, and should probably be retained.

For then shalt thou lift up thy (i) face without spot; yea, thou shalt be stedfast, and shalt not fear:
(i) He declares the quietness of conscience and success in all things that they shall have who turn to God in true repentance.

For then shall thou lift up thy face without spot,.... Either before men, being in all good conscience, walking in all the commandments and ordinances of the Lord, blameless, exercising a conscience void of offence towards God and men; and so be able to say as Samuel did, "whose ass have I taken?" &c. 1-Samuel 12:3; or rather before God, as in Job 21:26; using an holy boldness and an humble confidence with him at the throne of grace, in the view of the blood, righteousness, and sacrifice of his living Redeemer he had knowledge of, as every true believer may; who, though he is not without spot in himself, yet, being washed in the blood of Christ, and clothed in his righteousness, he is all fair, and without spot or wrinkle, or any such thing; and may stand before the throne without fault, and appear before God, and in his sight, unblamable and irreprovable:
yea, thou shalt be steadfast: firm and solid, rooted and grounded in the love of God; having a firm persuasion of interest in it, and that nothing shall separate from it; being built on the foundation of Christ, and established in the exercise of faith on him; the affections being steady towards him, and fixedly set on divine and heavenly things; continuing steadfast in the doctrines of grace, and not carried about with strange doctrines, or every wind of doctrine; as well as constant and immovable in the work of the Lord, always employed in his service, and doing his will, from which nothing can move; not reproach, affliction, and persecution; and to be thus steady and fixed is a great privilege:
and shalt not fear; evil tidings of evil times; of wars and rumours of wars, famine, pestilence, earthquakes, and other judgments; of changes and revolutions in kingdoms and states, or of what is coming upon the world, according to promise and prophecy, the heart being fixed and well established, trusting in the Lord; nor be afraid of evil men or devils, or any enemies whatever, nor of death, the king of terrors, that being one of the believer's blessings, and a friend of his; nor of hell and damnation, or the second death, or wrath to come; from all which the saints are secure.

Zophar refers to Job's own words (Job 10:15), "yet will I not lift up my head," even though righteous. Zophar declares, if Job will follow his advice, he may "lift up his face."
spot-- (Deuteronomy 32:5).
steadfast--literally, "run fast together," like metals which become firm and hard by fusion. The sinner on the contrary is wavering.

Lift up - Which denotes chearfulness, and holy boldness. Without spot - Having a clear and unspotted conscience. Steadfast - Shall have a strong and comfortable assurance of God's favour.