Shared ground
These two verses are primarily scene-setting. They place Israel and the Philistines in known staging areas (Aphek and Jezreel) and show that a battle is imminent. The Philistines are pictured as a coordinated coalition under multiple “lords,” moving in ordered groupings (“hundreds” and “thousands”), not as a loose raid.
A striking narrative fact is also explicit: David—an Israelite—is physically embedded in the Philistine army, attached to Achish, and his unit is placed at the rear. The text does not yet explain motives or outcomes, but it sharpens the tension by putting David on the wrong side of the battle line.
Where interpretation differs (only where needed)
Which “Aphek” is meant. Some argue for one specific site based on geography and likely military routes; others keep it general because multiple places shared the name. The theological point is usually not tied to identifying the exact mound, but the logistical picture can change depending on which site is chosen.
What “passed on” describes. Some read it as a straightforward marching order as units advance; others think it suggests a kind of review or inspection as leaders “pass by” with their troops. Either way, the shared meaning is an organized movement under commanders.
What David’s rear placement signals. Some think it implies limited trust or closer supervision; others see a routine placement for a contingent attached to a ruler; others consider it a tactical position (rear guard). The text itself only states the placement; it leaves the reason unstated.
Why the disagreement exists
The passage is brief and uses place names that can refer to more than one location. It also reports movements (“passed on”) and positions (“in the rear”) without giving the narrator’s explanation. That forces readers to infer motives from broader context (David with Achish) rather than from these verses alone.
What this passage clearly contributes
It establishes the battlefield geometry and the political-military reality: Philistia can marshal a multi-leader force, and Israel is encamped with access to water in Jezreel. Most importantly, it places David in a morally and politically fraught position—marching with the Philistines under Achish—while emphasizing his subordinate status by noting he is not at the front but in the rear. This sets up the conflict of loyalty that the chapter will soon address (1 Samuel 29:1–29:2).