The Psalms—so Hannah's song, etc., are the first introduction of the Remnant, on the failure of judicial and priestly economy, under Jehovah as their King—the only right thing short of Christ, and therefore introducing, in the hope and joy of the Remnant, at once the King, the Anointed (for prophecy was but a ministration of testimony)—Samuel when weaned from his mother, to be "before the Lord forever."
So all the Psalms are testimonies not of the Spirit from Jehovah to the people, but the Spirit of Christ in the Remnant towards Jehovah. You may sometimes see it speaking in the prophets as in Christ and them, but it is always prophetically" I fed the poor of the flock," “I and the children which God hath given me are for signs and wonders, etc."—so that it is still the same prophetic testimony; they knew that it was the Word of the Lord, but here it is the effect in the believing Remnant, and therefore in its highest character in Christ, which place, that He might be in them by His Spirit—take His place among them and lead them in Spirit, He expressly takes in Psa. 16, which is just its force.
This gives a special and interesting character to these Psalms; it amounts to prophecy when it is the actual expression of Christ's Spirit in the circumstances in which He was to be placed; still it was what He felt, and not what was declared about Him. “Thou wilt not leave my soul in hell; neither wilt thou suffer thine Holy One to see corruption"—we are not aware how. It is taking Jehovah as God that is so marked in the Psalms; i.e., the God of the Jews as the true God, “Who is God save Jehovah?” The Lord quite merges this. There are also often, I should add, answers by the Spirit to Messiah, so placed as in the Psalms, and expressing His mind holly therein; and also identification of Him with Jehovah, as in the New Testament with the Father.