Again, this verse should be seen in context and not as a general truth. There are times when God does not deal with us according to our sins, nor repay us according to our iniquities
(Psalm 103:10). But this psalm was composed at a time when Yahweh did deal with the people according to their sins.
Even though Moses was one of the four men (the others were Joshua, Caleb, and Aaron) who never doubted God’s promise to give the land Canaan to them, he did not try to set himself apart from the people. This can be seen by his continuous use of plural pronouns (“our iniquities,” “our secret sins”).
8 You have set our iniquities before you, our secret sins in the light of your presence.