1 Corinthians 16:21

The salutation of me Paul with mine own hand It was the custom of St Paul to employ an amanuensis. See Romans 16:22. But in order that the Epistle should be recognized as his, it was his custom to add a salutation in his own handwriting, which he wished to be regarded as a token of genuineness. 2 Thessalonians 3:17. See also Colossians 4:18 and Galatians 6:11 (where it seems to be implied that St Paul wrote the whole of that particular Epistle himself).