Thou art of purer eyes than to behold evil, and canst not look on iniquity: wherefore lookest thou upon them that deal treacherously, and holdest thy tongue when the wicked devoureth the man that is more righteous than he?
Thou art of purer eyes than to behold evil - without being displeased at it.
And canst not look on iniquity - unjust injuries done to thy people. The prophet checks himself from being carried too far in his expostulatory complaint, by putting before himself honourable sentiments of God.
Wherefore lookest thou upon them that deal treacherously - the Chaldeans, once allies of the Jews, but now their violent oppressors (cf. "treacherous dealers," Isaiah 21:2; Isaiah 24:16). Instead of speaking evil against God, he goes to God Himself for the remedy for his perplexity (Psalms 73:11-17).
And holdest thy tongue when the wicked devoureth the man that is more righteous than he? - the Chaldean oppresses the Jew, who, with all his faults, is better than his oppressor (cf. Ezekiel 16:51-52).