What Does Psalms 40:3 Mean?

Verse 3 gives the song-gift and the witness-response: "He put a new song in my mouth, a song of praise to our God. Many will see and fear, and put their trust in YHWH." The new-song put in the mouth (vayiten befiy shir chadash, and he put in my mouth a new song: the natan/give and the peh/mouth : verse 39:1's muzzled-mouth now filled by YHWH with a new-song; the shir-chadash/new-song of Psalm 33:3's sing-to-him-a-new-song and Revelation 5:9's new-song of the Lamb's redemption : the chadash/new because the rescue is new and the praise-response is freshly-given by the experience) of praise to our God (tehilla le'elohenu, a song of praise to our God: the tehillah/praise-song and the elohenu/our-God of the community-praise) and the many-will-see-and-fear-and-trust (yiru rabbim veyira'u uvitchu baYHWH, many will see and fear and will trust in YHWH: the rabbim/many who witness the rescue, fearing and trusting as the witnessed-rescue's impact: the ra'ah of seeing-and-being-impacted, the yare'/fear of the awe-and-reverence, and the batach/trust of Psalm 37:3's trust-in-YHWH now extended to the watching-rabbim who see the rescue).

The new-song-in-the-mouth (verse 3a) is the result of verse 2's rescue: the mouth that was muzzled (Psalm 39:1) and silent (Psalm 38:13-14) is now filled with YHWH-given song. The rescue (verse 2) produces the song (verse 3a) which produces the witness-impact (verse 3b): the rabbim-who-see-and-fear-and-trust form the community-of-trust that the individual's rescue has generated. This is the evangelistic function of the answered-prayer: YHWH rescuing the individual (verse 2) leads to the new-song (verse 3a) that produces the many trusting (verse 3b).

Revelation 5:9-10's "and they sang a new song, saying, 'Worthy are you to take the scroll and to open its seals, for you were slain, and by your blood you ransomed people for God from every tribe and language and people and nation'" is verse 3's shir-chadash (new song) in its eschatological Lamb-worship form: the new-song of verse 3a placed in the mouth by the rescue of verse 2 is the new-song of Revelation 5:9's redeemed-community worshiping the Lamb. Isaiah 61:3's "to give them a beautiful headdress instead of ashes, the oil of gladness instead of mourning, the garment of praise instead of a faint spirit" is verse 3's vayiten-befiy-shir-chadash (he put a new song in my mouth) in its Servant-ministry-form: the new-song/garment-of-praise replacing the faint-spirit (the pit-of-destruction of verse 2) is the Servant's work.