Following the death of Saul, the people who relied heavily on his military protection find themselves vulnerable and uncertain. David reaches out to the men of Jabesh-Gilead with a message of encouragement that blends the promise of military support with a careful political strategy. He urges them to remain strong and brave, taking up arms to fight their own battles with courage. Their primary protector, Saul, who had always fought on their behalf, is now dead [מצודת דוד, מלבי״ם, שטיינזלץ]. This call to bravery is specifically intended to prevent them from following the example of other Israelites who, paralyzed by weakness after Saul's fall, abandoned their cities. Instead, David encourages them to stand firm and continue fighting the enemies of God as true men of valor [אברבנאל].
To offer them a new source of hope and stability, David informs them that the house of Judah has anointed him as their king. The primary approach among commentators is that David shares this news to calm their fears of being left defenseless. He wants to assure them that his strength is in no way inferior to Saul's, and that he will stand by their side to help them in times of distress.
However, this message also addresses a deeper, twofold anxiety within the community. The men of Jabesh-Gilead likely feared that David might seek revenge against them for their fierce loyalty to his former rival, Saul. Furthermore, they might have felt insecure knowing that David's current rule extends only over Judah, rather than the entirety of Israel. By reaching out, David promises that despite these concerns, they have no reason to lose heart, as he will look upon them with favor and grant them his protection [אלשיך].
Ultimately, beyond merely offering defense, David speaks with the clear authority of a monarch. His decision to announce his kingship over Judah is a calculated move designed to draw the men of Jabesh-Gilead closer to him, paving the way for them to eventually accept his leadership as well [אברבנאל, שטיינזלץ].