Deviseth — Expresses what thy wicked mind had devised. Deceitfully — Doeg pretended only to vindicate himself from disloyalty, 1 Samuel 22:8, but he really intended to expose the priests, to the king's fury.
Related Commentaries of Psalms 52:2
Psalms 52:2
2 Thy tongue deviseth mischiefs; like a sharp razor, working deceitfully.