Charles H. Spurgeon on Psalms 119:39

Turn away my reproach which I fear. He feared just reproach, trembling lest he should cause the enemy to blaspheme through any glaring inconsistency. We ought to fear this, and watch that we may avoid it. Persecution in the form of calumny may also be prayed against, for it is a sore trial, perhaps the sorest of trials to men of sensitive minds. Many would sooner bear burning at the stake than the trial of cruel mockings. David was quick tempered, and he probably had all the greater dread of slander because it raised his anger, and he could hardly tell what he might not do under great provocation. If God turns away our eyes from falsehood, we may also expect that he will turn away falsehood from injuring our good name. We shall be kept from lies if we keep from lies.

For thy judgments are good. Therefore he is anxious that none may speak evil of the ways of God through hearing an ill report about himself. We mourn when we are slandered; because the shame is cast rather upon our religion than ourselves. If men would be content to attribute evil to us, and go no further, we might bear it, for we are evil; but our sorrow is that they cast a slur upon the word and character of God, who is so good, that there is none good in comparison with him. When men rail at God's government of the world it is our duty and privilege to stand up for him, and openly to declare before him, "thy judgments are good"; and we should do the same when they assail the Bible, the gospel, the law, or the name of our Lord Jesus Christ. But we must take heed that they can bring no truthful accusation against us, or our testimony will be so much wasted breath.

This prayer against reproach is parallel to Psalms 119:31, and in general to many other of the seventh verses in the octaves, which usually imply opposition from without and a sacred satisfaction within. Observe the things which are good: "thy judgments are good; ""thou art good and doest good" (Psalms 119:68); "good for me to have been afflicted" (Psalms 119:71); "teach me good judgment" (Psalms 119:66).