John Gill Commentary 1 Samuel 29:1

"Now the Philistines gathered together all their hosts to Aphek: and the Israelites encamped by the fountain which is in Jezreel." — 1 Samuel 29:1 (ASV)

Now the Philistines gathered together all their armies to
Aphek
Not the city in the tribe of Judah of that name, (Joshua 15:53) ; where the Philistines had a camp in the time of Samuel, (1 Samuel 4:1) ; but rather that in the tribe of Asher, (Joshua 19:30) ; unless there was one of this name in the tribe of Issachar, not mentioned, since it seems to have been near Jezreel and Shunem, which were both in that tribe, (Joshua 19:18) ;

and the Israelites pitched by a fountain which is in Jezreel ;
in the valley of Jezreel; of which (See Gill on Joshua 19:18) and (See Gill on Hosea 1:5).