Ps. 149

¹ "a new song,"

How to sing a new song? If child finds a coin on the road, he takes it and sings a new song by himself. He is the writer of that new song. When you are happy you will sing. When you are sad you will sing. Every situation in a human life had a song. It may be a birthday, death day, marriage. Every occasion has a song. If you have feelings about something, singing cannot be a difficult thing. When we see the Lord, we cannot help but sing. A new song is not difficult if we have feelings about the Lord. 

 "in the assembly of his faithful people"

The writer is talking about a public worship. 

   ²  Maker; King.
A person who makes something is the creator of it. And the one who buys it, is the king of it. Jesus is both. 

³ ...praise his name with dancing
Let the blood move while you praise him since the life is in the blood.

 ...and harp.
Once you strike the harp, the sound sustains. Some have a gratitude that does not sustain for a while. Hos. 6:4

⁴ For the LORD takes delight in his people;

   he crowns the humble with victory.

⁵ Let his faithful people rejoice in this honor

   and sing for joy on their beds.

   ⁶ May the praise of God be in their mouths
   and a double-edged sword in their hands,
⁷ to inflict vengeance on the nations
   and punishment on the peoples,
⁸ to bind their kings with fetters,
   their nobles with shackles of iron,
⁹ to carry out the sentence written against them—
   this is the glory of all his faithful people.

   Praise the LORD.