Psalm 58:10

The righteous will be glad when they are avenged, when they dip their feet in the blood of the wicked. 

The righteous will be glad 
Job 22:19-20  "The righteous see their ruin and rejoice; the innocent mock them, saying, 'Surely our foes are destroyed, and fire devours their wealth.' "

when they are avenged 
Deuteronomy 32:35  "It is mine to avenge; I will repay. In due time their foot will slip; their day of disaster is near and their doom rushes upon them."
Psalm 7:9  Bring an end to the violence of the wicked and make the righteous secure--you, the righteous God who probes minds and hearts.
Psalm 91:8  You will only observe with your eyes and see the punishment of the wicked.
Jeremiah 11:20  But you, LORD Almighty, who judge righteously and test the heart and mind, let me see your vengeance on them, for to you I have committed my cause.
Romans 12:17-21  Do not repay anyone evil for evil. Be careful to do what is right in the eyes of everyone. If it is possible, as far as it depends on you, live at peace with everyone. Do not take revenge, my dear friends, but leave room for God's wrath, for it is written: "It is mine to avenge; I will repay," says the Lord. (Deuteronomy 32:35) On the contrary: "If your enemy is hungry, feed him; if he is thirsty, give him something to drink. In doing this, you will heap burning coals on his head." (Proverbs 25:21-22) Do not be overcome by evil, but overcome evil with good.

when they dip their feet in the blood of the wicked 
Psalm 68:23  " ... that your feet may wade in the blood of your foes, while the tongues of your dogs have their share."

(parentheses are mine)

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