Charles Ellicott Commentary 2 Samuel 3:22

"And, behold, the servants of David and Joab came from a foray, and brought in a great spoil with them: but Abner was not with David in Hebron; for he had sent him away, and he was gone in peace." — 2 Samuel 3:22 (ASV)

Joab came. —He had been either on some expedition against the Philistines, the Amalekites, or other enemies of Judah, or else engaged in repelling some attack from them. In either case, he returned elated with victory, and bringing great spoil; but Abner had concluded his interview and gone away before his return.