How are their mouths wrong?
Rashi: They (Radak - Shorerai) appear like lovers, but they are enemies.
Malbim: 'Peh' implies external speech; their Peh speaks nice matters. 'Lashon' is speech with counsel and intellect; their Lashon is guile and flattery to destroy [David].
Why does it say "Nechonah" (feminine)?
Radak: The noun that it describes, e.g. Amrah or Dibrah, is omitted. We find like this - "u'Ma'achalo Beri'ah" (Chabakuk 1:16; its food is a fat Seh. Seh is omitted - Radak there), "k'Eder ha'Ketzuvos" (Shir ha'Shirim 4:2; it should say 'k'Eder Rechelim ha'Ketzuvos'. Rechelim is omitted - Ibn Ezra there), "v'Ashir Ya'aneh Azos" (Mishlei 18:23; Imros Azos - Ibn Ezra there).
What is "Havos"?
Rashi: It is thoughts of deception.
Radak: They are evil thoughts.
Why does it say "Kever Pasu'ach Geronam"?
Radak: One who does not guard himself from them, and hears their flattery, they look like friends, and he falls b'Kivramm, i.e. in their evil thoughts. It is called Garon, like "Romemus Kel bi'Gronam" (149:6), for some letters are said in the throat 1 . Also, all speech begins in the throat; the voice comes from the throat and causes speech in the mouth. Also, the throat is open to the innards, which are compared to the grave.
Malbim: It is as if their innards are the grave, into which the Mes descends before it goes to She'ol (Gehinom), and destruction.
I.e. the gutturals - Aleph, Hei, Ches and Yud. (PF)
What is the meaning of "Yachalikun"?
Rashi: [They speak] words of deception.
Malbim: Their tongues are like a dark, slippery place; one who goes there slips and falls into their throat, i.e. the pit and the grave, and from there to their innards - destruction and She'ol.
