John Gill Commentary 1 Samuel 26:5

"And David arose, and came to the place where Saul had encamped; and David beheld the place where Saul lay, and Abner the son of Ner, the captain of his host: and Saul lay within the place of the wagons, and the people were encamped round about him." — 1 Samuel 26:5 (ASV)

And David arose, and came to the place where Saul had pitched ,
&c.] Came near it, within sight of it; so that he could take a view of it with his naked eye, and observe where and in what manner he was encamped:

and David beheld the place where Saul lay, and Abner the son of Ner ,
the captain of his host ;
where he and his general had their quarters in the camp:

and Saul lay in the trench ;
or circuit; not in the foss or ditch thrown up, in which an army sometimes lies entrenched; but this is to be understood either of the camp itself, so called, as Ben Gersom, Abarbinel, and Ben Melech think, because it lay in a circular form, that all comers to it on every side might be seen; or else a sort of fortress all around the camp, made of carriages joined together; and as the word signifies a carriage, cart or chariot, it may design the chariot in which Saul slept, as kings have been used to do when not in their houses; and to this the Septuagint agrees, which uses a word that Procopius Gazaeus says signifies one kind of a chariot, and is used of a chariot drawn by mules, in the Greek version of (Isaiah 66:20) ; Grotius observes, kings used to sleep in chariots where there were no houses; (See Gill on 1 Samuel 17:20); though he rather seems to have slept, "sub die", in the open air:

and the people pitched round about him ;
both for the sake of honour, and for his greater security; this shows it could not be the loss he laid in, for then they could not pitch around him.