Psalms 52:2

Deviseth i.e. expresseth what thy wicked mind had devised. Thus skilfulness is ascribed to those hands which are governed by a skilful or prudent man, Psalms 78:72. This word implies that Doeg’s words were not uttered rashly and unadvisedly, but with premeditated malice, and a mischievous design, which he waited for an opportunity to execute; and therefore he readily took the first occasion which offered itself.

Like a sharp razor, working deceitfully; wherewith a man pretending only to shave off the hair, doth suddenly and unexpectedly cut the throat. So Doeg pretended only to vindicate himself from the imputation of disloyalty, 1 Samuel 22:8, but really intended to expose the priests, who were friends to David, to the king’s fury and cruelty.