חסידות אויף משלי 24:6

And this is a great principle in serving G-d, even to other people [who are not wicked], to each and every person according to his level: whenever he wants to further himself in serving G-d, the evil inclination rises and strengthens against him more. This has already been explained elsewhere, and we must be perceptive regarding this - and "With tactics shall you wage war" (Proverbs 24:6) to strengthen against the evil with a great strengthening, every time. Happy is he who merits to win the war.