As it appears in the Douay-Rheims, Psalm 149 is prefaced with:
“Cantate Domino. The church is particularly bound to praise God. Alleluia.” It truly is a “Hymn on the establishment of the kingdom of the LORD” and that Kingdom is the Church.
 Sing ye to the Lord a new canticle: let his praise be in the church of the saints.
“A festive atmosphere pervades the entire Psalm.” I think the same can be said for the next and final Psalm of the Psalter as well. The last six psalms all begin with “praise.”
 Let Israel rejoice in him that made him: and let the children of Sion be joyful in their king.
“But as many as received him, he gave them power to be made the sons of God, to them that believe in his name. Who are born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.” All are born of God in their first birth, but those born anew are those who accept their King, the Christ. It is they who, faithfully enduring til the end, will hear “enter thou into the joy of thy lord.”
 Let them praise his name in choir: let them sing to him with the timbrel and the psaltery.
 For the Lord is well pleased with his people: and he will exalt the meek unto salvation.
“The protagonists of the Psalm in the original Hebrew text are given two terms that are taken from the spirituality of the Old Testament. Three times they are defined as the hasidim (vv. 1, 5, 9), ‘the pious, the faithful ones’, who respond with fidelity and love (hesed) to the fatherly love of the Lord.” “Blessed are the meek, for they will inherit the land.” This, as many of the beatitudes, goes against our first inclinations, but truly, it is the meek that inherit the new creation:
 The saints shall rejoice in glory: they shall be joyful in their beds.
 The high praise of God shall be in their mouth: and two-edged swords in their hands:
“Do not suppose that I have come to bring peace to the earth. I did not come to bring peace, but a sword.”  “For the word of God is living and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart.”
 To execute vengeance upon the nations, chastisements among the people:
“The kings of the earth stood up, and the princes met together, against the Lord and against his Christ. Let us break their bonds asunder: and let us cast away their yoke from us.”
 To bind their kings with fetters, and their nobles with manacles of iron.
We are told in the second Psalm: “The One enthroned in heaven laughs; the Lord scoffs at them. Then he rebukes them in his anger and terrifies them in his wrath, saying, ‘I have installed my King on Zion, my holy hill.’”
 To execute upon them the judgment that is written: this glory is to all his saints.
“And Jesus said to them: Amen, I say to you, that you, who have followed me, in the regeneration, when the Son of man shall sit on the seat of his majesty, you also shall sit on twelve seats judging the twelve tribes of Israel.”
Dr. Daniel Van Slyke, Notes on Processional and Enthronement Psalms
 John Paul II, General Audience, Wednesday 23 May 2001
 John 1:12-13
 Matt 25:23
 Augustine, Sermones, 33, 1
 John Paul II
 Matt 10:34
 Heb 4:12
 Psalm 2:2-3
 Psalm 2:4
 Matt 19:28