C. F. Keil and Franz Delitzsch on 1 Samuel 29:4

1Sa 29:4

But the princes, i.e., the four other princes of the Philistines, not the courtiers of Achish himself, were angry with Achish, and demanded, “Send the man back, that he may return to his place, which thou hast assigned him; that he may not go down with us into the war, and may not become an adversary (satan) to us in the war; for wherewith could he show himself acceptable to his lord (viz., Saul), if not with the heads of these men?” הלוא, nonne, strictly speaking, introduces a new question to confirm the previous question. “Go down to the battle:” this expression is used as in 1Sa 26:10; 1Sa 30:24, because battles were generally fought in the plains, into which the Hebrews were obliged to come down from their mountainous land. “These men,” i.e., the soldiers of the Philistines, to whom the princes were pointing.