8 Hence the threatening countenance, the lowering aspect, pallor in the face, trembling on the lips, gnashing of the teeth, mad words, unbridled revilings, a hand prompt for the violence of slaughter; even if for the time deprived of a sword, yet armed with the hatred of an infuriate mind. And accordingly the Holy Spirit says in the Psalms: “Be not jealous against him who walks prosperously in his way.” And again: “The wicked shall observe the righteous, and shall gnash upon him with his teeth. But God shall laugh at him; for He sees that his day is coming.” The blessed Apostle Paul designates and points out these when he says, “The poison of asps is under their lips, and their mouth is full of cursing and bitterness. Their feet are swift to shed blood, destruction and misery are in their ways, who have not known the way of peace; neither is the fear of God before their eyes.”
Source: The Treatises of Cyprian (New Advent)