Why does it say "Pesi Ya'amin lChol Davar"?
Rashi #1: He believes their words and is enticed to follow them.
Rashi #2: He believes talebearers.
R. Yonah: The verse teaches that even though it is good to hear counsel (refer to 14:14:2:2), this harms Pesayim. They do not distinguish between Sug Lev and Yesharim, or between stupid and proper counsel.
Malbim: Above, it taught that the Kesil and Evvil, their heart is bothered. They are not secure in their ways. Pesi lacks Da'as, and is enticed like a silly dove without a heart. He believes everything, including words of a Kesil and Evvil, without distinction. His heart does not bother him at all.
What is the meaning of "v'Arum Yavin la'Ashuro"?
Rashi: He considers his steps. He anticipates a quarrel, and waits until he knows [whether he heard] properly.
R. Yonah: One who has Sechel and investigates, Sugei Lev will not deceive him. He hears the counselors' words, and when he must act, he weighs their words and chooses the straight path to go in it.
Malbim: Arum is the opposite of Pesi. His heart has Armah to test everything. He is not enticed. He understands what will help his spiritual happiness and success, and does it. "Chachmas Arum Havin Darko" (8), "Kol Arum Ya'aseh v'Da'as" (13:16).
