Charles Ellicott 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)

Aphek. —The name Aphek was a common one and was given to several strongholds in Canaan. It signifies a fort or a strong place. This Aphek was most likely situated in the Plain of Jezreel. Eusebius places it in the neighborhood of En-dor.

By a fountain which is in Jezreel. —By a fountain. The Septuagint wrongly adds “dor,” supposing the spring or fountain to be the well-known En-dor—spring of Dor—but En-dor, as we know, lay many miles away from Saul’s camp. This “fountain” has been identified by modern travelers as Ain-Jalûd, the Fountain of Goliath, because it was traditionally regarded as the scene of the old combat with the giant.

It is a large spring, flowing from under a cavern in the rock that forms the base of Gilboa. “There is every reason to regard this as the ancient fountain of Jezreel, where Saul and Jonathan pitched before their last fatal battle, and where, too, in the days of the Crusades, Saladin and the Christians successively encamped.”—Robinson, Palestine, Vol. 3, pp. 167-168.