O let the nations be glad and sing for joy,.... As they were glad, and did sing for joy, and glorified God, when Christ was made known, and the Gospel was preached unto them, Ac 8:5.for thou shalt judge the people righteously; meaning not the people of the world at the last day, at the general judgment, which will be a righteous one; when God will judge the world in righteousness, according to the strict rules of justice and equity, by him whom he has ordained, Ps 96:1; but either the righteous judgment which will be executed on the enemies of Christ's church and people; particularly on antichrist, which will be matter of great joy, Re 19:1; and Kimchi interprets it of the judgment of the nations which shall come with Gog and Magog; or else the judging and vindicating the Lord's own people, defending their cause, righting their wrongs, and suffering no weapon to prosper against them;and govern the nations upon earth; or "lead [them]" ; not to punishment, as Kimchi, who interprets this clause as the other; but by his grace and Spirit, into the knowledge of his way, and saving health; or as a shepherd leads his flock into green pastures, and beside the still waters; or as a king leads and governs his people, as David guided the people of Israel, with the skilfulness of his hands; so Christ leads and governs his people, protects and defends them, holds them by his right hand, guides them with his counsel, and then receives them to glory; see Ps 23:2.
Selah; on this word, See Gill on "Ps 3:2".