R. Yonah: Refu'ah of the tongue helps only those who want to hear and accept rebuke, just like Etz ha'Chayim helps those who take from its fruits and eat, but not for Evilim and Letzim, who hate rebuke - "Yoser Letz Loke'ach Lo Kalon u'Mochi'ach l'Rasha Mumo" (9:7).

Malbim: Musar is built on fear. He afflicts the powers of his Nefesh via reminding it of the punishments that come to one who veers from the way of Chachmah. This requires Da'as, that he knows that there is a Supervisor who rewards and punishes, and he fears Him. With this he will receive Musar - "Ohev Musar Ohev Da'as" (12:1). A Kesil knows the laws of Chachmah, just his desire overpowers him [so he transgresses the laws]. He does not accept Musar, but he does not hate it in his heart. If not for desire and the Yetzer, he would accept Musar and go in the ways of Chachmah. Av Evvil is unsure about everything. He does not love Da'as. He despises Musar in his heart, for he does not believe in Hashem's punishments and Hashgachah. Rebuke is built on the Sechel showing the benefit of Chachmah. The Evvil does not despise this as long as he is prepared to accept matters of intellect.

R. Yonah: The Evvil hates rebuke and refuses to listen. One who does not hate Musar, and wants to hear, and bends his ear to hearken, even though he left the category of Evilim, he does not fulfill his obligation until he guards the rebuke in his heart, lest he forget it. Then, he will get wise. This Shemirah is to guard and do - "Tishmerun La'asos" (Devarim 8:1).

Malbim: A Ba'ar, an animalistic person who does not understand Sechel's concepts at all - "Sonei Sochachas Ba'ar" (ibid.) The opposite of Ba'ar and Pesi is one that Armimus entered his heart; he begins to distinguish between good and evil. One who guards rebuke, he leaves being a Ba'ar and goes to Armah.