Why does it say "v'Asosem Resha'im"?
Rashi: This is an expression of pressing, like "v'Sham Isu Dadei Besuleihen" (Yechezkel 23:3).
Radak: This is trampling and crushing. A liquid that comes via crushing and squeezing is called Asis. Nowadays, Resha'im rule over you. Then, you will trample them under your feet.
Malbim: They will thresh the Resha'im until they are like an Isah (dough).
Here it says that you will trample Resha'im. It says that they will be ashes, and verse 19 said that the sun will burn them!
Radak: They will not be eradicated in one day. It will be gradually, in a short time. As long as they last, you will trample them. It says ashes for a Mashal, since it said that the sun will burn them.
Malbim: The burning heat will make them like ashes, and you will thresh the ashes until they are like a dough.
What is "ba'Yom Asher Ani Oseh"?
Radak: It is the day of judgment, when I will judge them.
