Matthew Henry on 1 Samuel 29:6–end
If the reasons Achish had to trust David were stronger than the reasons which the princes offered why they should distrust him (as I do not see that, in policy, they were, for the princes were certainly in the right), yet Achish was but one of five, though the chief, and the only one that had the title of king; accordingly, in a council of war held on this occasion, he was over-voted, and obliged to dismiss David, though he was extremely fond of him. Kings cannot always do as they would, nor have such as they would about them.
I. The discharge Achish gives him is very honourable, and not a final discharge, but only from the present service. 1. He signifies the great pleasure and satisfaction…
Read the whole note in the consoleJamieson-Fausset-Brown on 1 Samuel 29:4
the princes of the Philistines were wroth with him--It must be considered a happy circumstance in the overruling providence of God to rescue David out of the dangerous dilemma in which he was now placed. But David is not free from censure in his professions to Achish (Sa1 29:8), to do what he probably had not the smallest purpose of doing--of fighting with Achish against his enemies. It is just an instance of the unhappy consequences into which a false step--a departure from the straight course of duty--will betray everyone who commits it.
Adam Clarke on 1 Samuel 29:6
Thou hast been upright - So he thought, for as yet he had not heard of the above transaction; David having given him to understand that he had been fighting against Israel.
John Gill on 1 Samuel 29:7
Wherefore now return,.... To Ziklag:
and go in peace; not only in a peaceable manner, easy and satisfied, as David was at his very heart to hear this, but all prosperity and happiness attend thee; the Jews (n) distinguish between wishing persons to go in peace, and to go to peace; the former they observe has not issued happily, when the other has, and they instance in the wish of Jethro to Moses, and of David to Absalom:
that thou displease not the lords of the Philistines: and what would be the consequence of that he could not say, but suggests it would be most for his peace and safety to depart.
(n) T. Bab. Beracot, fol. 64. 1. Sepher Alphes, par. 1. fol. 421. 2.