Rashi: His anger will kill a fool like you! Had you been silent, perhaps Midas ha'Rachamim would have turned to you.

Devar Eliyahu: Man has two Yetzers - anger and desire. Kin'ah branches off from desire. Some Resha'im are enticed by desires of this world, and do not see the good. Others understand in their hearts that there is no substance in worldly desires. However, they do not want to refrain from them - they are Evilim. Corresponding to this, there are two kinds of death. (a) Sudden death, due to anger. (b) Death after a long illness - he gets weaker until he dies. It can happen also due to envy. Every day his heart sours, until he dies. Chazal said, if [the Yetzer ha'Ra] is a rock, it will melt - i.e. if his Yetzer ha'Ra is stubborn like a rock (he is an Evil), it will melt in Torah, which is called water. If it is iron, it will shatter. I.e. if he is heated and easily angered, like iron, which is easily heated in fire, it shatters in the fire of Torah. "Le'Evil Yaharag Ka'as" - an angry person, his anger will kill him.

Malbim: Since you were Evil, and unsure about Hashem's Hashgachah, it is not proper that Hashem's word and Kedoshim appear to you. Also, you deny choice, and say that man is forced in his deeds due to the stars, which decree about everything - Elifaz clarified that this is false. We find that anger kills an Evil - it is not due to a previous decree. Rather, he chose anger and envy; this caused his loss. This shows that man has choice; evil choice causes his death.

Rashi: Here, Kin'ah is anger, like "Hem Kin'uni."

Devar Eliyahu: One who is enticed will die from his envy. Refer to 5:2:1:2. Here it mentions Misah, which is natural; it comes slowly. Harigah (due to anger) is sudden, from anger.