These wars, though here related, were transacted long before this time: of which See Poole on "2 Samuel 21:1". For it is no way probable, either that the Philistines, being so fully and perfectly subdued by David, 2 Samuel 8:1, should in his days be in a capacity of waging war with the Israelites; or that David in his old age would undertake to fight with a giant, or that his people would permit him to do so.
Related Commentaries of 2 Samuel 21:15
2 Samuel 21:15
15 Moreover the Philistines had yet war again with Israel; and David went down, and his servants with him, and fought against the Philistines: and David waxed faint.