The Ziphites came to Saul to Gibeah, saying, Doesn't David hide himself in the hill of Hachilah, which is before the desert?
"David saw the place where Saul lay, with Abner ... commander of his army"  (1 Samuel 26:5).  Willis suggested that David must have arrived in daylight; but as both the king and Abner were asleep, it appears more likely that a brilliant moonlight enabled, not David, but the spies he sent to come back with this report.  The word "saw" here is idiomatic as in  1 Samuel 26:4.  David did not enter Saul's camp until later in the night.