Psalm 55:21 in the King James Version
The words of his mouth were smoother than butter, but war was in his heart: his words were softer than oil, yet were they drawn swords.
Context
20 He raises his hands against his friends. He has violated his covenant.
21 His mouth was smooth as butter, but his heart was war. His words were softer than oil, yet they were drawn swords.
22 Cast your burden on the LORD and he will sustain you. He will never allow the righteous to be moved.