Psalm 149 Chiasm

A   Praise Yah!
B     the faithful sing
C       the true king
D         physical praise
E            Yhwh delivers
F               the faithful exult
E'            we fight for God
D'         physical violence
C'       the false kings
B'     the faithful execute judgment
A' Praise Yah!

Exodus Collection Psalms 90-106

Book IV could be summarised as the Exodus collection, as they reference key events in the Psalms as follows:

Exodus 1-2 (calling out in affliction)	Ps 90.0, 13-17 (by Moses)
Exodus 3-12 (Plagues)	Ps 91.3-4, 11
Exodus 13.3 (brought out of land of slavery)	Ps 92.9
Exodus 14-15 (crossing of the sea)	Ps 93.3-4
Review of the story so far	Ps 94 (vibe)
Exodus 15.20-21 (Miriam's song of joy by the sea)	Ps 95.1-7
Exodus 17.7 (testing and strife / Massah and Meribah)	Ps 95.8-11
Exodus 24 (sacrifice; glory appears)	Ps 99.6-7
Exodus 34.6 (Yhwh, Yhwh, gracious & merciful)	Ps 103 Yhwh Gracious & merciful
Whole story positively	Ps 105
Whole story negatively	Ps 106

Summarised from Michael Wilcock's Bible Speaks Today Ps 73-150

I put this down because I was working through Psalm 95, where God is the Rock of Salvation.

I hadn't thought much of the link until i then read 1 Corinthians 10.1-4:

1 Corinthians 10 1 For I do not want you to be ignorant of the fact, brothers, that our forefathers were all under the cloud and that they all passed through the sea. 2 They were all baptized into Moses in the cloud and in the sea. 3 They all ate the same spiritual food 4 and drank the same spiritual drink; for they drank from the spiritual rock that accompanied them, and that rock was Christ.

All this together makes me rethink what it for Ps 95.1 to talk about the Rock of our Salvation. Originally I thought it was a general reference to God as a rock - a very common metaphor. But from the macro-structure of Book IV of the Psalms, I now think it's a specific reference to the rock in the desert, when the people were complaining, God instructed Moses to strike it with his staff and water came out for the people to drink.

1 Cor 10.4 tells us the rock was Christ, the living water which sustained God's people in the wilderness. So it is appropriate that we call upon our rock, our firm foundation, who sustained his people in the desert, and sustains us now with the living water, which fully satisfies.