What is the meaning of "Mah Masa Hashem"?
Rashi: It is an expression of jesting, for his Nevu'ah was a Masa (burden) to them.
Radak: Hashem investigates hearts and tests kidneys (7:10). He knows that you say Masa, for you consider His words to be a burden. Therefore He commanded Yirmeyah to warn them not to ask about Devar Hashem in an expression of Masa.
Malbim: Nevu'ah is called Masa, for a Navi bears his words in parables and metaphors. In the days of Yirmeyah they mocked words of Nevu'ah, and said "ha'Lo Memashel Meshalim Hu" (Yechezkel 1 21:5). Yirmeyah did not have any Nevu'ah called Masa, for all his Nevu'os were about the Churban; for this he did not bear a parable or metaphor 2 . When people asked about his Nevu'ah and told each other, they converted the style to parables and metaphors. He warned them about both - (a) When they ask "Mah Masa", which is an expression of jesting, and it also means that the Dibur is a burden to Hashem
Yechezkel's prophecy began 30 year into the exile (Yechezkel 1:1). Perhaps Malbim means that just like then, they mocked, also now. (PF)
We find this in his Nevu'os - "ha'Tzari Ein b'Gil'ad" (8:22), "Mekunant ba'Arazim Mah Nachanta" (22:23)! Perhaps Malbim means that it is much less than in other Nevi'im. (PF)
What Navi is this?
Radak: It is a false Navi.
Radak citing Targum Yonasan: Refer to 23:11:1:2.
What Kohen is this?
Radak: It is a Kohen from Levi (Zera Aharon).
What is the meaning of "v'Natashti"?
Rashi: I will abandon. They say, what is the burden (Nevu'ah, which we are loathe to hear)? You are a burden to Hashem. He will abandon and cast you off His arms from Shamayim to Aretz! So I heard.
