John Gill Commentary 1 Samuel 29:9

"And Achish answered and said to David, I know that thou art good in my sight, as an angel of God: notwithstanding the princes of the Philistines have said, He shall not go up with us to the battle." — 1 Samuel 29:9 (ASV)

And Achish answered and said to David
In reply to the questions:

I know that thou [art] good in my sight as an angel of God :
for his great wisdom, and graceful behaviour, and inoffensive carriage:

notwithstanding the princes of the Philistines have said, he shall not
go up with us to the battle ;
though Achish had so good an opinion of him, and had declared it in council, yet an order had passed there that he should not go to battle with them; there were but five of them, and Achish was one of the five, so that there were four to one for the dismissing him; and Achish, though a king, was obliged to submit.