David sent out spies to verify that Saul had arrived.
Here, 1. Saul gets information of David's movements and acts offensively. The Ziphites came to him and told him where David now was, in the same place where he was when they formerly betrayed him, Sa1 23:19. Perhaps (though it is not mentioned) Saul had given them intimation, under-hand, that he continued his design against David, and would be glad of their assistance.
Commenting on 1 Samuel 26:1-5
David therefore sent out spies,.... To observe if he was coming or come, and where he was, that he might not be surprised by him; for though David knew the Lord was and would be his protection, he thought proper to be upon his guard, and to make use of means for his safety: and understood that Saul was come in very deed; that he...
David . . . sent out spies . . . and David arose, and came to the place where Saul had pitched--Having obtained certain information of the locality, he seems, accompanied by his nephew (Sa1 26:6), to have hid himself, perhaps disguised, in a neighboring wood, or hill, on the skirts of the royal camp towards night, and waited to approach it under covert of the darkness.