Cover not — Let their wickedness be in thy sight, so as to bring down judgments upon them, that either they may be reformed, or others may be warned by their example. God is said to cover or hide sin when he forbears to punish it. Provoked thee — They have not only provoked us builders, but thee also.
Related Commentaries of Nehemiah 4:5
Nehemiah 4:5
5 And cover not their iniquity, and let not their sin be blotted out from before thee: for they have provoked thee to anger before the builders.