While we are saved by grace, we are to be JUDGED by works.
This is explicit in Revelation 20:12-13, the Parables in Luke 19 and Matthew 25. It's all about judgment according to works.
Judgment according to works for the unbeliever, not the believer. Since the unbeliever has nothing but his works to appeal to for salvation, that’s what’s going to be used to judge him.
The believer’s works are evaluated at the Judgment Seat of Christ and tested to prove their worth, but the believer is already saved by grace through faith in Christ, not as a result of works so that no one has cause to boast about himself.