Psalm 108 is a composite psalm, woven from earlier songs of David, and St Augustine explicitly reads it "not in the surface of the history, but in the depth of prophecy." The result is not patchwork but concentration: a ready heart that sings before dawn, a prayer that God's glory rise above the heavens, and a closing confession that the help of man is vain.
Read and follow along: https://orthodoxbiblestudy.com/bible-studies/old-testament/psalms/psalm-108-lxx-107-o-god-my-heart-is-ready