Charles Ellicott Commentary Psalms 21:12

"For thou wilt make them turn their back; Thou wilt make ready with thy bowstrings against their face." — Psalms 21:12 (ASV)

(12) Therefore. —Literally, for thou shalt put them shoulder (pones eos dorsum, Vulgate). Upon thy strings thou shalt aim against the face of them. Ewald renders: “Shalt strike them back;” but the English version seems to explain rightly. To “give the neck of an enemy” (Psalms 18:4) is a similar form of expression.