2 Samuel 17:12. We will light upon him as the dew falleth upon the ground — Plenteously, suddenly, irresistibly, and on all sides; for so the dew falls. This is very beautiful and expressive. “The dew in Palestine, as in several other climates, falls fast and sudden; and is therefore an apt emblem of an active and expeditious soldiery. And it was, perhaps, for this reason that the Romans called their light armed forces, rorarii. The dew falls upon every spot of the earth; not a blade of grass escapes it. A numerous army resembles it in this respect; it is able to search everywhere.” — Delaney.

17:1-21 Here was a wonderful effect of Divine Providence blinding Absalom's mind and influencing his heart, that he could not rest in Ahithophel's counsel, and that he should desire Hushai's advice. But there is no contending with that God who can arm a man against himself, and destroy him by his own mistakes and passions. Ahithophel's former counsel was followed, for God intended to correct David; but his latter counsel was not followed, for God meant not to destroy him. He can overrule all counsels. Whatever wisdom or help any man employs or affords, the success is from God alone, who will not let his people perish.As the dew - Like the drops of dew, in the vast number of our host, and in our irresistible and unavoidable descent upon our enemies. 12. we will light upon him as the dew falleth on the ground—No image could have symbolized the sudden onset of an enemy so graphically to an Oriental mind as the silent, irresistible, and rapid descent of this natural moisture on every field and blade of grass. As the dew falleth on the ground, i. e. plenteously, suddenly, irresistibly, and on all sides; for so the dew falls.

So shall we come upon him in some place where he shall be found,.... For such a numerous army, which would be spread abroad, could not well fail of finding him out, let him be in what lurking place he would; whereas he might lie concealed, and escape so small a number as twelve thousand men:

and we will light upon him as the dew falleth upon the ground; whose drops are innumerable, and cover all the ground where they fall; and the phrase not only expresses their numbers, but the irresistible force they should come with, and the manner, secretly, unawares, opportunely; the Romans had a sort of soldiers, called from the dew "rorarii", who carried light armour, and fought first in the battle, from whence they had their name, because dew falls before it rains (n):

and of him, and of all the men that are with him, there shall not be left so much as one; so that for the future Absalom would sit easy upon the throne, there being none left to molest him.

(n) Valtrinus de Milit. Roman. l. 3. c. 3.

So shall we come upon him in some place where he shall be found, and we will light upon him as the dew falleth on the ground: and of him and of all the men that are with him there shall not be left so much as one.