John Gill Commentary Psalms 18:38

"I will smite them through, so that they shall not be able to rise: They shall fall under my feet." — Psalms 18:38 (ASV)

I have wounded them, that they were not able to rise
Which was not only true of the Amalekites, but of all with whom David engaged in war;

they are fallen under my feet ;
either dead, or become subject and tributaries to him; as the Philistines, Moabites, Syrians, and Edomites; see (2 Samuel 8:1 2 Samuel 8:2 2 Samuel 8:5 2 Samuel 8:14) .

This, with (Psalms 18:37) , may very well be accommodated to David's antitype, and be expressive of the entire victory he has obtained over all his and his people's enemies; he wounded the heads over many countries, (Psalms 110:6) . Satan and his principalities and powers, whose head is broke, whose works are destroyed; yea, he himself, which had the power of death, so as not to be able to rise more against Christ, who has led captivity captive: he has also finished and made an end of sin, and overcome the world; nor did he turn back from this work he engaged in until he had made a complete conquest; and moreover he has likewise made his people more than conquerors, through him, over these same enemies; so that the words are also applicable to them.