Daniel 10:13

10:13 However, the prince of the kingdom of Persia was opposing me for twenty-one days. But Michael, one of the leading princes, came to help me, because I was left there with the kings of Persia.

Daniel 10:20

10:20 He said, “Do you know why I have come to you? Now I am about to return to engage in battle with the prince of Persia. When I go, the prince of Greece is coming.