This prayer of thanksgiving (also recorded in Psalm 18) appears near the end of David's story. But David likely prayed it much earlier in his life. This prayer and Hannah’s prayer in 1 Samuel 2:1–10 together enclose the book of Samuel with an inclusio (literary bookends). Hannah was saved from being unable to have children, and David was saved from his enemies.
The hymn's placement also provides a parallel to Moses. Both Moses and David's stories end with a song praising God (see also Deuteronomy 31:30–32:43). Both emphasize God as a “Rock” (Deuteronomy 32:4, 15, 18, 30, 31; 2 Samuel 22:2, 3, 32, 47). Both are followed by second and shorter poetic pieces:
the final blessing of Moses to the Israelite tribes (Deuteronomy 33), and
David’s last words (2 Samuel 23:1–7).