He guards the steps of His faithful ones, but the wicked perish in darkness; for by his own strength shall no man prevail. — 1 Samuel 2:9

"by his own strength shall no man prevail". David knew this facing goliath with a sling, and the horse is a vain hope for salvation. Paul learned it most deeply: "my grace is sufficient for you, for my power is made perfect in weakness". Your strength fails. His doesn't.