What is the meaning of "Chazu [Shav]"?
Rashi: It is an expression of Nevu'ah.
Malbim: Their vision is empty and non-existent. It is merely their imagination.
What is "Kesem Kazav"?
Radak: Sometimes their words are fulfilled. "Modi'im l'Chadashim me'Asher Yavo'u Alayich" (Yeshayah 47:13) - me'Asher (some) [of what will come upon you], but not all. Therefore, they were enticed to their words, and said that they had vision from Hashem. It was false.
Malbim: Their predictions of the future are Kezev ? it will not be like they say.
Why does it say "ha'Omerim Ne'um Hashem"?
Malbim: They attributed their Sheker to Hashem. Really, Hashem did not send them.
Why does it say "v'Yichalu Lekayem Davar"?
Rashi #1: How do they expect (hope) to fulfill their words (Malbim ? since there is no existence to their words themselves, and Hashem did not send them)?!
Rashi #2: It is an expression of waiting.
Radak: Yisrael hope to fulfill their words ? it is not realized.
