Who shall declare his way to his face? - That is, the face of the wicked. Who shall dare to rise up and openly charge him with his guilt? The idea is, that none would dare to do it, and that, therefore, the wicked man was not punished according to his character here, and was reserved to a day of future wrath.
And who shall repay him what he hath done? - The meaning is, that many wicked people lived without being punished for their sins. No one was able to recompense them for the evil which they had done, and consequently they lived in security and prosperity. Such were the tyrants and conquerors, who had made the world desolate.