Thought he was based on Dan 1. Seven times in that chapter it refers to the prince of eunuchs. "Then said Daniel to Melzar, whom the prince of the eunuchs had set over Daniel, Hananiah, Mishael, and Azariah,"
They had been taken by Nebuchadnezzar, required to learn the literature and language of the Chaldeans, given different names, supervised by eunuchs, and told what to eat though it was the same food as the king's.
But don't see where it specifically states it.