C. F. Keil and Franz Delitzsch on Proverbs 27:4

Pro 27:4 4 The madness of anger, and the overflowing of wrath -    And before jealousy who keeps his place!

Here also the two pairs of words 4a stand in connection; אכזריּוּת (for which the Cod. Jaman has incorrectly אכזריות) is the connecting form; vid., regarding אכזרי, Pro 5:9. Let one imagine the blind, relentless rage of extreme excitement and irritation, a boiling over of anger like a water-flood, which bears everything down along with it - these paroxysms of wrath do not usually continue long, and it is possible to appease them; but jealousy is a passion that not only rages, but reckons calmly; it incessantly ferments through the mind, and when it breaks forth, he perishes irretrievably who is its object. Fleischer generalizes this idea: “enmity proceeding from hatred, envy, or jealousy, it is difficult or altogether impossible to withstand, since it puts into operation all means, both secretly and openly, to injure the enemy.” But after Pro 6:34., cf. Sol 8:8, there is particularly meant the passion of scorned, mortified, deceived love, viz., in the relation of husband and wife.