John Trapp on Isaiah 41:15

Ver. 15. I will make thee a new ſharp threſhing inſtrument having teeth] Traham, aut tribulam in omnem partem probè dentatam. Such as thoſe Eaſtern Countries did uſe, to maſh in pieces their rougher and harder fodder for their cattle; or rather to threſh out their harder grain with, Chap. 28.25, 28. or to torture men with, 2 Sam. 12, 31.

Thou ſhalt threſh the mountains] Thy lofty and mighty enemies. This was fulfilled in the Macchabees: But eſpecially in the Apoſtles, ſubduing the Nations to the obedience of the Faith: See 2 Cor. 10.4.