Reference: Now the reprised text is from Micah rather than Isaiah:
Micah 5:8-9
8 ¶ And the remnant of Jacob shall be among the Gentiles in the midst of many people as a lion among the beasts of the forest, as a young lion among the flocks of sheep: who, if he go through, both treadeth down, and teareth in pieces, and none can deliver.
9 Thine hand shall be lifted up upon thine adversaries, and all thine enemies shall be cut off.
This was first cited in 3 Nephi 20:16-17. This text is being used as the proof-text for the role-reversal of the last days where the restored Israel destroys the wicked of the world, here represented by the collective term, Gentiles.