ישעיהו יג:יז פירוש: רש״י ואבן עזרא

Behold I stir up Media against them Darius the Mede assassinated Belshazzar. So Scripture states (Dan. 5:30): “On that very night, Belshazzar...was slain”; (ibid. 6:1) “And Darius the Mede acquired the kingdom.”

The Medes, who are the most cruel people.

and do not desire gold They do not care [for anything,] but to kill and to avenge the harm the kings of Babylon did to all the peoples.