Arise, O God! plead thy cause. The pious Jews again supplicate God to ascend into his judgment-seat. He is then said to arise, when, after having long exercised forbearance, he shows, in very deed, that he has not forgotten his office as judge. To induce him to undertake this cause the more readily, they call upon him to maintain his own right. Lord, as if they had said, since the matter in hand is what peculiarly concerns thyself; it is not time for thee to remain inactive. They declare, at the same time, how this was, in a special sense, the cause of God. It was so, because the foolish people daily cast reproaches upon him. We may here again translate the word nvl, nabal, the worthless people, instead of the foolish people. The wickedness charged against the persons spoken of is aggravated from the circumstance, that, not content with reproaching God on one occasion, they continued their derision and mockery without intermission. For this reason, the faithful conclude by invoking God that he would not forget such heaven-daring conduct in men who not only had the audacity to reproach his majesty, but who fiercely and outrageously poured forth their blasphemies against him. They seemed, it is true, to do this indirectly; but, as they despised God, it is asserted that they rose up against him with reckless and infatuated presumption, after the manner of the Giants of old, and that their haughtiness was carried to the greatest excess.

Arise, O God - As if God were now insensible to the wrongs and sufferings of his people; as if he were inattentive and indisposed to come to their help. See the notes at Psalm 3:7.
Plead thine own cause - literally, "Contend thine own contention." That is, Maintain a cause which is really thine own. Thine own honor is concerned; thine own law and authority are assailed; the war is really made on "thee." This is always the true idea in the prayers which are offered for the conversion of sinners, for the establishment of truth, and for the spread of the Gospel in the world. It is not originally the cause of the church; it is the cause of God. Everything in regard to truth, to justice, to humanity, to temperance, to liberty, to religion, is the cause of God. All the assaults made on these, are assaults made on God.
Remember how the foolish man reproacheth thee daily - Constantly. He does not cease. The word "foolish" refers to the wicked. The idea is, that the wicked constantly reproach God - either by their language or their conduct; and this is a reason for calling on him to interpose. No better reason for asking his interposition can be given, than that such conduct is a real reproach to God, and reflects on his honor in the world.

Plead thine own cause - Thy honor is concerned, as well as our safety and salvation. The fool - the idolater, reproacheth thee daily - he boasts of the superiority of his idols, by whose power, he asserts, we are brought under their domination.

Arise, O God, plead thine (p) own cause: remember how the foolish man reproacheth thee daily.
(p) He shows that God cannot permit his Church to be oppressed unless he looses his own right.

Arise, O God, plead thine own cause,.... The church's cause being the cause of God; and therefore she desires that he would arise and exert himself, and take vengeance on his and her enemies: this is an interesting argument, and a forcible one:
remember how the foolish man reproacheth thee daily; this being so frequently repeated, as in Psalm 74:10, shows how much the name and glory of God lay near her heart; the Targum is,
"remember the reproach of thy people by a foolish king all the day;''
perhaps the man of sin is meant, the king of the locusts, and angel of the bottomless pit.

(Compare Psalm 3:7; Psalm 7:6). God hears the wicked to their own ruin (Genesis 4:10; Genesis 18:20).