How do a Kesil's lips come to argue?
Rashi: All his words are confronting.
R. Yonah: When people argue, it is normal to get angry at the other's words after he is stubborn and does not admit. However, when a Kesil answers his colleague, his initial words are strife and anger, for he habituated his lips to quarrel. "Yavo'u" shows that they are used to arguing without prior thought.
Malbim: The lips speak external speech. When a Kesil asks this (why is there Tzadik v'Ra Lo?) with his external lips, he already comes in an argument against Hashgachah.
What is the meaning of "u'Fiv l'Mahalumos Yikra"?
Rashi: He calls to afflictions to bring them on himself.
R. Yonah: This is an expression of announcing and screaming. The same applies to "Yikra Ish Chasdo" (20:6). He screams and raises his voice to strike his opponent, to weary him. We learn from here to beware of raising the voice in rebuke and argument - "Divrei Chachamim b'Nachas Nishma'im" (Koheles 9:17).
Malbim: The mouth speaks internal speech with Chachmah. When he speaks with his mouth, according to the depth of Chachmah, he strengthens the feud to the point of hitting. He will want to prove from this that [Hashem's] conduct is against the laws of Chachmah.
