John Gill Commentary 1 Kings 20:14

"And Ahab said, By whom? And he said, Thus saith Jehovah, By the young men of the princes of the provinces. Then he said, Who shall begin the battle? And he answered, Thou." — 1 Kings 20:14 (ASV)

And Ahab said, by whom ?
&c.] Knowing he had no army with him sufficient to go out with against the Syrian army:

and he said, thus says the Lord, even by the young men of the princes
of the provinces ;
either such, as Kimchi thinks, who were brought up with him; or, as others, the sons of governors of
provinces, who were kept as hostages, that their fathers might not rebel; neither of which is likely: but
rather the servants of such princes who waited on them, and lived delicately and at ease, and were not
trained up to military exercise, even by these should the victory be obtained:

then he said, who shall order the battle ?
begin the attack, we or they? or who shall conduct it, or be the general of the army, go before it, and lead
them on? Ahab might think, being an idolater, that the Lord would not make use of him, or otherwise who could
be thought of but himself?

and he answered, you ;
you must be the commander, go forth with the army, and make the attack upon the enemy.