Why boastest thou thyself in mischief, O mighty man? the goodness of God endureth continually.
Continually — God is continually doing good: thou art continually doing mischief.
O mighty — He speaks ironically. O valiant captain! To kill a few weak and unarmed persons.
 Thy tongue deviseth mischiefs; like a sharp razor, working deceitfully.
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.
 God shall likewise destroy thee for ever, he shall take thee away, and pluck thee out of thy dwelling place, and root thee out of the land of the living. /*Selah*/.
Pluck thee — Violently and suddenly as the Hebrew word signifies, from thy house and lands, and all the wages of thy righteousness.
Root — Though thou seemest to have taken deep root, yet God shall pluck thee up by the very roots, and destroy thee both root and branch.
 The righteous also shall see, and fear, and shall laugh at him:
Fear — Reverence God's just judgment.
 But I am like a green olive tree in the house of God: I trust in the mercy of God for ever and ever.
The house — In God's church, or among his people.
 I will praise thee for ever, because thou hast done it: and I will wait on thy name; for it is good before thy saints.
Thou hast — Destroyed mine and thine implacable enemies, and established me in the throne, of which I am no less assured, than if it were already done. I will continue in thy way, placing my whole confidence in thy power and goodness, and faithfulness.
Before — In the presence of thy saints.