David meets a crossroads where he has to now determine who his loyalty is towards, Israel or the Philistines.
The narrative is paralleled with Saul at Endor, for Saul has received a judgment from God, to be killed by the Philistines and end with David's reign, with David now marching with the Philistines.
The Philistine commanders object to David fighting with them (vv. 3–5).
The commanders quote the song of the women of Israel from ch. 18.
Their fear is that David will turn on them mid-battle to buy back Saul's favor (v. 4).
Achish swears by the God of Israel that David will serve him, when David has deceived him for months.
David's words can be read either way, "I may not go and fight against the enemies of my lord the king?"
David is told to go back to Ziklag because of the suspicion of the commanders.
God's providence works through the hostility of unbelievers, and the deliverance is provided even though David has not asked for it.
God providentially restricts David from being involved, directly or indirectly, in the coming death of Saul, as to preserve him from such a great sin as bringing his hand against the Lord's anointed.