Matthew Henry's Complete Bible Commentary
Verses 3—4
These two verses show the intolerable mischief, 1. Of ungoverned passion. The wrath of a fool, who when he is provoked cares not what he says and does, is more grievous than a great stone or a load of sand. It lies heavily upon himself. Those who have no command of their passions do themselves even sink under the load of them. The wrath of a fool lies heavily upon those he is enraged at, to whom, in his fury, he will be in danger of doing some mischief. It is therefore our wisdom not to give provocation to a fool, but, if he be in a passion, to get out of his way. 2. Of rooted malice, which is as much worse than the former as coals of juniper are worse than a fire of thorns. Wrath (it is true) is cruel, and does many a barbarous thing, and anger is outrageous; but a secret enmity at the person of another, an envy at his prosperity, and a desire of revenge for some injury or affront, are much more mischievous. One may avoid a sudden heat, as David escaped Saul’s javelin, but when it grows, as Saul’s did, to a settled envy, there is no standing before it; it will pursue; it will overtake. He that grieves at the good of another will be still contriving to do him hurt, and will keep his anger for ever. MHBCC 656.3