Which day is discussed?
Radak: It is in the days of Mashi'ach 1 , when Hashem will judge the Resha'im.
Radak: There are still idols of silver and gold in the far east.
What will they do with their idols?
Rashi: They will cast them in the clefts that they find when they come to flee and hide. Radak - they do so disgracefully, for the idols did not help them. If they will be saved, they will break them for the sake of the silver and gold, and not for idols. (Also refer to 2:20:3:1*.)
What is the meaning of "[Lehishtachavos] la'Chpor Peros"?
Rashi: They are idols in the forms of moles 1 - rodents that dig in the ground. Radak - "Peros" is like Chafiros (holes dug out in the ground). We find like this - 'Pira di'Shfulei' (Kidushin 73b; cavities in which they cast date pits).
Radak: "La'Chpor" refers to "Yashlich"; they will cast the idols into the cavities.
Radak citing Targum Yonasan: "La'Chpor" refers to "Lehishtachavos"; they bow to idols in this form. "La'Chpor Peros" is like one word 2 ; it is a bird that pecks at fruits.
Malbim: Early idolaters attributed divinity to forms of living beings in the settled land, Midbar, sea and birds, and even despised rodents that dwell in holes in the ground. They thought that each has power in its locale. They served each when they needed help in its region, e.g. the form of an ox when they needed to plow in the ground. When they needed to hide in clefts and cavities, they would bow to moles and bats. In the future, just the contrary - when they go to hide there, they will discard their idols.
Metzudas Tziyon: The Pei and Reish are repeated, to teach that they are deep [holes], just like Adamdam is very red, Yerakrak is very yellow and similar words.
