Jamieson, Fausset and Brown on Isaiah 13:3

3. sanctified ones--the Median and Persian soldiers solemnly set apart by Me for the destruction of Babylon, not inwardly "sanctified," but designated to fulfil God's holy purpose (Jr 51:27, 28; Joe 3:9, 11; where the Hebrew for prepare war is "sanctify" war).

for mine anger--to execute it.

rejoice in my highness--"Those who are made to triumph for My honor" [Horsley]. The heathen Medes could not be said to "rejoice in God's highness" Maurer translates, "My haughtily exulting ones" (Zep 3:11); a special characteristic of the Persians [Herodotus,1.88]. They rejoiced in their own highness, but it was His that they were unconsciously glorifying.