Charles Ellicott Commentary 2 Samuel 12:28

"Now therefore gather the rest of the people together, and encamp against the city, and take it; lest I take the city, and it be called after my name." — 2 Samuel 12:28 (ASV)

The rest of the people. —Joab proposes a general muster of the remaining forces of Israel, either because additional force was actually needed for the capture of the citadel, or simply to carry out the formal capturing of the city by David in person.