10:5 a garrison of the Philistines. The mention of a Philistine garrison foreshadows the task ahead for the one designated to deliver the people of God from the Philistines (9:16). On the stationing of garrisons in subject territories, see David’s practice in 2 Sam. 8:6.
group of prophets. Samuel is associated with a group of prophets in 19:20, where he is described as their leader. Note the similar association of Elisha with the “sons of the prophets” in 2 Kin. 2; 6:1; 9:1; etc. These prophetic guilds appear to have been made up of defenders of true religion in times of widespread apostasy and spiritual indifference.
prophesying. Prophecy in the Old Testament is often, though not exclusively, associated with the giving of a message (see Aaron’s role as Moses’ “prophet” or spokesman in Ex. 7:1; and compare Ezek. 21:9; Amos 3:8). God’s prophets were His messengers (2 Sam. 7:1–5; 12:1; 24:11–12). In some places, prophecy is associated with music (Ex. 15:20, 21; 1 Chr. 25:1). The prophesying in view here seems to be praising God and exhorting the people with musical accompaniment.