Charles Ellicott Commentary Psalms 55:21

"His mouth was smooth as butter, But his heart was war: His words were softer than oil, Yet were they drawn swords." — Psalms 55:21 (ASV)

The words of his mouth. —The ancient versions and the grammatical anomalies point to a corruption of the text. Read, Smoother than butter is his face. The reading face for mouth is suggested by the Septuagint, though their version has wandered far from the text even thus amended.

Drawn swords. —The comparison of the tongue to a sword is frequent; that of the words themselves not so usual, but apt. We may compare Shakespeare’s “I will speak daggers to her, but use none.”—Hamlet.