What is the meaning of "Lechem Yudak"?
Rashi: What is [ground] finely with hard matters? Bread of grain 1 , for it is not easy to beat it [to remove the chaff].
Radak: Yudak is like Yudash (it is threshed, i.e. via Charutz and a wagon wheel). It says Yudak due to the straw; it is minced, until the seed inside is seen.
Malbim: If one wants to make bread, he must remove the shell that sticks to the grain. Threshing does not suffice. He must grind it in a mill, or mash it in a mortar. A Charutz and wagon wheel remove external chaff, but not the shell.
Radak: I.e. wheat, barley and spelt, from which we make bread.
Why does it say "Ki Lo la'Netzach Adush"?
Rashi: Here, Ki means rather. One does not crush it forever, for the seeds are not crushed via Charutz and a wagon wheel.
Radak (28, 29): They are threshed for a fixed limited time. The one who threshes understands that it is threshed. The Nevi'im will not warn forever. If crops are beaten too much, they are ruined. Similarly, excessive warning of the Navi is spoiled if people do not accept it. Nations will say 'they are a foolish nation, without a heart' - the opposite of what they say when they guard Hashem's way, "Rak Am Chacham v'Navon" (Devarim 4:6). Refer to 28:24:1:2.
Kli Paz: The affliction that I send against Yehudah will not be permanent.
Malbim: One does not thresh forever, for it only removes external chaff, but does not grind it finely to remove the shell.
Why does it say "Adush Yedushenu"?
Rashi: This is like "Aso Ya'aseh" (Yechezkel 31:11), "Tzanof Yitznafcha" (above, 22:18). The Aleph is in place of a Hei, like "v'Acharei Chen Eschabar Yehoshafat" (Divrei ha'Yamim II, 20:35) is like Hischabar. Here, it is like Hadush Yedushenu. Also Menachem says so.
Radak: The Aleph is extra.
Kli Paz: Adush is first person; Hashem speaks. (I thresh, i.e. afflict Yisrael to improve them.)
What is the meaning of "v'Hamam Gilgal Eglaso u'Farashav"?
Rashi: When they turn wagon wheels to mince and thresh it, even the wheel is damaged and breaks, and similarly other Kelim of the wagon with it, which remove the grain from its straw, it will not be minced and the wheat will not be ground.
Radak: He will not put the wheel on it for a long time, nor the Charutz, lest the seeds be broken and crushed.
Malbim: A Charutz and wheel remove external chaff, but "Lo Yedukenu" (they do not grind it - only a mill or mortar does). Similarly, if mistakes or bad thoughts cling to one's essence, rebuke alone is not enough; he needs also afflictions.
