1 Samuel 27:1

And David said in his heart
Within himself, and to himself; while he was pondering things in his own mind, and considering the circumstances in which he was, and things appearing, very gloomy to him, he falls into a fit of unbelief and thus addresses himself:

I shall now one day perish by the hand of Saul;
for though he was returned to his place, he knew he was restless and uneasy, very inconstant and unstable, and not at all to be depended on; yea, he might conclude that Saul, observing that God was with him in protecting and defending him, and by delivering him into his hands once and again, he would be the more jealous of him, and envious at him, and seek all opportunities and advantages against him; and he feared that one time or another such would offer, and would be taken, and so he should perish by him: this was a strange fit of unbelief he was sunk into, and very unaccountable and unreasonable it was, had he but considered his being anointed king by the Lord, the promise of God to him, which could not fail, and the providence of God that watched over him from time to time:

[there is] nothing better for me than that I should speedily escape
into the land of the Philistines;
which may seem strange, when he was advised by the Prophet Gad to depart from the land of Moab, and go into the land of Judah, ( 1 Samuel 22:5 ) , and where he had been so wonderfully preserved; and when he was in so much danger, when in the land of the Philistines before, insomuch that he was obliged to feign himself mad, ( 1 Samuel 21:13 ) ; and seeing this also was the very thing he lately dreaded, and cursed the men that should be the cause of his going out of his own land into an idolatrous one:

and Saul shall despair of me, to seek me any more in any coast of
Israel;
hearing that he was gone into a foreign country, would seek for him no more in any part of the land of israel, and so despair of ever getting him into his hands, would lay aside all thoughts about him for the future:

so shall I escape out of his hand;
and be for ever safe: these were the carnal reasonings of his mind, under the prevalence of unbelief; and shows what poor weak creatures the best of men are, and how low their graces may sink as to exercise, when left to themselves.