Why does it say "Lachen"?
Radak: You deny Me and My Nevu'ah. My words apply to you!
Why does it say "Daberchem"?
Radak: Hashem addresses the nation. When He says "b'Ficha", He addresses Yirmeyah.
Radak citing Targum Yonasan: He addresses their [false] Nevi'im.
Why does it say "I will put My words in your mouth"?
Radak: Through this, they will recognize that My Nevu'ah came to you. The evil will be fulfilled on them like you say.
What is the meaning of "v'Achalasam"?
Rashi: [The fire] will consume them.
Malbim: You are like wood destined to be burned in the fire. I.e. the punishment will come immediately with the Navi's words, just like fire immediately burns wood once it touches it. Since they deny and do not believe, there is no solution for them.
