The psalmist, having exhorted the judges, 1-4, and reproved their negligence, 5-7, prays God to judge, 8.
1 [A Psalm of Asaph.] God stands in the congregation of the mighty. He judges among the gods.
2 "How long will you judge unjustly and accept the persons of the wicked?" [Selah.]
3 "Defend the poor and fatherless. Do justice to the afflicted and needy.
4 Deliver the poor and needy. Deliver them from the hand of the wicked.
5 They do not know, neither will they understand. They walk on in darkness. All the foundations of the earth are out of course.
6 I have said, 'You are gods, and all of you are children of the Most High.
7 But you shall die like men and fall like one of the princes.'"
8 Arise, O God, judge the earth, for you will inherit all nations.
Matthew Henry Commentary - Psalms, Chapter 82
John Calvin's Chapter Summary:
As kings, and such as are invested with authority, through the blindness which is produced by pride, generally take to themselves a boundless liberty of action, the Psalmist warns them that they must render an account at the bar of the Supreme Judge, who is exalted above the highest of this world. After he has reminded them of their duty and condition, perceiving that he speaks to such as refuse to receive admonition, he calls upon God to vindicate his character as a righteous judge.
[v.6] - Quoted in John 10:34.