Thou hast delivered me from the strivings of the people. David now approaches his conclusion. In one verse he at once sums up his past deliverances and anticipates fresh glories. God has delivered him from the strivings of those who were hostile to him among his own people (see Psalms 18:4-18), and has also given him victory over the heathen.
In the future he will do even more. And thou hast made me the head of the heathen. The antithesis between "people" ( עָם) and "heathen," or "nations" ( גוֹיָם), is unmistakable. The long series of David's victories have made him "head" over the latter.
This is less clearly seen in the history of David's reign than in the description given of the state of the kingdom inherited from David by Solomon (1 Kings 4:21, 1 Kings 4:24). A people whom I have not known shall serve me.
It is not clear that this was ever fulfilled literally in the person of David, and, we are entitled to explain it as a Messianic prophecy, parallel with that of Psalms 2:8.