New; and therefore sharper and stronger than another which hath been much used. Sharp threshing instrument having teeth; such as were usual in those times and places, of which See Poole on "Isaiah 28:25", See Poole on "Isaiah 28:28". The mountains; the great and lofty potentates of the world, which set themselves against thee; such persons being frequently expressed in Scripture under the notion of hills and mountains.
Related Commentaries of Isaiah 41:15
Isaiah 41:15
15 Behold, I will make thee a new sharp threshing instrument having teeth:f thou shalt thresh the mountains, and beat them small, and shalt make the hills as chaff.