For fear of the briers and thorns, you will no longer traverse the hills once tilled by the hoe; they will become places for oxen to graze and sheep to trample.
KJV
And [on] all hills that shall be digged with the mattock, there shall not come thither the fear of briers and thorns: but it shall be for the sending forth of oxen, and for the treading of lesser cattle.
ASV
And all the hills that were digged with the mattock, thou shalt not come thither for fear of briers and thorns; but it shall be for the sending forth of oxen, and for the treading of sheep.