C. F. Keil and Franz Delitzsch on 2 Samuel 19:7

2Sa 19:7 “And now rise up, go out and speak to the heart of thy servants (i.e., speak to them in a friendly manner: Gen 34:3; Gen 50:21, etc.): for I swear by Jehovah, if thou go not out, verily not a man will stay with thee to-night; and this will be worse to thee than all the evil that has come upon thee from thy youth until now.” Joab was certainly not only justified, but bound in David’s own interests, to expostulate with him upon his conduct, and to urge him to speak in a friendly manner to the people who had exposed their lives for him, inasmuch as his present conduct would necessarily stifle the affection of the people towards their king, and might be followed by the most serious results with reference to his throne. At the same time, he did this in so heartless and lordly a manner, that the king could not fail to be deeply hurt by his words.