John Trapp on Psalms 68:21

Verſ. 21. But God ſhall wound the [illegible: 1 word] of his enemies] [illegible: 1 word] caput, a wound in the head if deep (and God ſtrikes no ſmall blows) is mortal. Chriſt will break the head of thoſe that bruiſe his heel, that attempt any thing againſt Him, and his. By Head here Diodate underſtandeth the Devil, that Prince of the World, Deut. 32.42. Pſal. 110.6. Hab. 3.13. Evil ſpirits in Scripture are called Shegnirim, ſhag-haired, Levit. 17.7. Iſa. 13.21. And they go on in their treſpaſſes; they do infinitely hate God, and ſin that ſin againſt the Holy Ghoſt every moment. But the moſt underſtand it of wicked men.

And the hairy ſcalp of ſuch a one as goeth on ſtill, &c.] This is Gods enemy, that by his wilful wickedneſs ſtriketh, and as it were ſhooteth at God, runneth upon him, even upon his neck, and upon the thick boſſes of his Bucklers, Job 15.25, 26. his hairy ſcalp, ſetting forth his fierceneſs, Job 5.5. Note this againſt Anti-Roundheads. See Ezek. 44.20.