תהילים ב:ט פירוש: רש״י ורד״ק

You shall break them Heb. תרעם [like] תרוצצם.

Thou shalt break (הרעם) them with a rod of iron: – And so He says to me of all the nations that shall rise up against me, Thou shalt break them with a rod of iron.

with an iron rod That is the sword.