First Chronicles 10 records Saul’s death and the events preceding and following it. Because he did not want to be abused by his uncircumcised enemies (10:4) after he had been wounded (10:3), Saul fell on his own sword and died (10:4-6). The Israelites who were with him deserted their cities and fled (10:7), resulting in the Philistines taking over the cities.
On the next day, the Philistines found the dead bodies of Saul and his sons (10:8). They stripped him, cut off his head, and took it and his armor and sent people around their land (10:9a-b) “to carry tidings unto their idols, and to the people” (10:9c). They then “put his armor in the house of their gods, and fastened his head in the temple of Dagon” (10:10).
The LXX rendering of 10:9 is instructive:
LXE 1 Chronicles 10:9 And they stripped him, and took his head, and his armour, and sent them into the land of the Philistines round about, to proclaim the glad tidings to their idols, and to the people.
BGT 1 Chronicles 10:9 καὶ ἐξέδυσαν αὐτὸν καὶ ἔλαβον τὴν κεφαλὴν αὐτοῦ καὶ τὰ σκεύη αὐτοῦ καὶ ἀπέστειλαν εἰς γῆν ἀλλοφύλων κύκλῳ τοῦ εὐαγγελίσασθαι τοῖς εἰδώλοις αὐτῶν καὶ τῷ λαῷ
Because their enemy had been destroyed, the Philistines sent people out to proclaim that good news to both their idols and their people. The verb used here (εὐαγγελίζομαι) is used in the NT for preaching the good news of Jesus Christ (e.g., Acts 14:7).
The great enemy of mankind, Satan, has been destroyed (cf. Heb. 2:14-15; 1 John 3:8). We should continually be praising and thanking our God for His destroying Satan through the work of His Son, and we should be proclaiming His doing so as good news throughout and to the whole world (cf. Acts 10:36-43, especially 10:38)!