Psalm 99:1-3. The Lord reigneth, let the people tremble — Namely, such of them as are enemies to God and his truth. He sitteth between the cherubims — Upon the ark; that is, he is present with his people, to protect them and punish their enemies. Let the earth — Namely, the people of the earth; be moved — With fear and trembling. The Lord is great in Zion — Hebrew, The Lord in Zion (that is, who dwelleth in Zion) is great. He is high above all people — Above all the people of the earth who exalt themselves against him. Let them — Namely, all people last mentioned; praise thy great and terrible name — And give thee the glory due unto it; for it is holy — As well as great, and therefore worthy to be praised. The holiness of God’s name makes it truly great to his friends and terrible to his enemies.

Psalm 99:4. The king’s strength also loveth judgment — “Although the strength of our king be infinite, yet is it never exerted but in righteousness and just judgment, which are his delight. They compose the firm basis of his throne, and direct his whole administration.” “Whoever peruses this Psalm,” says Dr. Dodd, “will find that David here, as everywhere else, considers God as the king of Israel, and himself only as his deputy. To this purpose are these expressions in the beginning of it, The Lord reigneth: The Lord is great in Zion. It is true David delighted to exert all the power that God had given him to its true purposes. He loved judgment and righteousness: but it was, in reality, God who executed them all.” Thou dost establish equity — God gave them the excellent laws by which they were governed, and acted toward them with equity in all his proceedings. Thou executest judgment in Jacob — Among thy own people, whom, when they act amiss, thou punishest no less than thou dost other people, (see Psalm 99:8,) whereby thou showest that thou art no respecter of persons, but a righteous and impartial judge to all sorts of men. He intends also that God, not only by his immediate providences often executed and enforced his own laws, but that he took care for the administration of justice among them by civil magistrates, who reigned by him, and by him did decree justice. These judges judged for God, and their judgment was his, 2 Chronicles 19:6.

Psalm 99:5. Exalt ye the Lord — Give him the glory of the good government you are under, as it is now established. And worship at his footstool — That is, at his ark, which was the footstool to the mercy-seat, between the cherubim. Or we must cast ourselves down upon the pavement of his courts; and good reason we have to be thus reverent, for he is holy, and his holiness should strike an awe upon us, as it doth on the angels themselves, Isaiah 6:2-3. Observe, reader, that God is to be worshipped and glorified, is the one inference always drawn from every position of David. And surely the greater the public mercies are in which we have a share, the more we are obliged to bear a part in the public homage paid to God. The setting up of the kingdom of Christ, especially, ought to be matter of our praise. Observe further, when we draw nigh to God to worship him, our hearts ought to be filled with high thoughts of him, and we ought to exalt him in our souls. And the more we abase ourselves, and the more prostrate we are before God, the more we exalt him.

Psalm 99:6. Moses and Aaron among his priests, &c. — Or, with his princes, as the Hebrew, בכהניו, may be rendered, or his chiefs; that is, his principal and most famous ministers. Moses, however, might with propriety be ranked among the priests, because, before the institution of the priesthood, he executed that office, and because he often interceded with God for the people; which was a very considerable part of the priests’ work. And Samuel — Who used frequently and solemnly to intercede with God on behalf of the people. The meaning is, “Thus did Moses, and Aaron, and Samuel also, one of the greatest of those prophets who were wont to intercede for you.” Thus he urges them to perform the duty of praising and worshipping God, by the examples of three most eminent persons, who practised this duty with happy success.

Psalm 99:7. He spake unto them in the cloudy pillar — That is, to some of them: to Moses frequently, and to Aaron sometimes, as Numbers 12:5. And although it is not anywhere expressly said that God spake unto Samuel out of the cloudy pillar, yet, as Dr. Hammond observes, it is probable enough from his history that he did so; for when Samuel was so signally heard by God at Mizpeh, 1 Samuel 7., it is said, 1 Samuel 7:9, The Lord answered him; and 1 Samuel 7:10, The Lord thundered with a great thunder, which supposes a cloud, if not a cloudy pillar; and so this answering of Samuel with thunder, must be God’s speaking to him at this time out of the cloud. They kept his testimonies — This is added, not only for their commendation, but for the instruction of the Israelites, to teach them that God would not hear the prayers of them who did not keep his commandments.

Psalm 99:8. Thou answeredst them, O Lord — Namely, the intercessors before mentioned. Thou forgavest them — Either, 1st, Moses and Aaron, who sinned, and whose sins God pardoned, yet so that he punished them with exclusion from the land of Canaan. Or rather, 2d, The people, for whom they prayed; for this forgiving was evidently the effect of God’s answering the prayers of the persons above mentioned; and, therefore, as their prayers, recorded in Scripture, were not for the pardon of their own, but for the pardon of the people’s sins, so this forgiveness granted was for the sins of the people. Though thou tookest vengeance of their inventions — This clause limits and explains the former. Thou didst forgive the sins of the people, not absolutely and universally, for thou didst punish them severely, but so far as not to inflict that total and final destruction upon them which they deserved, and thou hadst threatened: see Exodus 32:10; Exodus 32:14; Exodus 32:34.