This greeting is in my own hand, Paul’s. This is the sign in every letter; this is how I write. The grace of our Lord Jesus Christ be with all of you. (2 Thes 3:17-18)
Paul didn’t want to have more problems with fake letters allegedly from him . . . so after the scribe who had been furiously trying to write down everything that the apostle dictated, Paul signs the letter in his own hand. I wonder how much that autograph would be worth today?