An horse — Though he be strong and fit for battle, or for flight, if need requires. And so this is put for all warlike provisions. Vain things — Heb. a lie; because it promises that help and safety which it cannot give.
Related Commentaries of Psalms 33:17
Psalms 33:17
17 An horse is a vain thing for safety: neither shall he deliver any by his great strength.