12 Then they came near, and spake before the king concerning the king's decree; Hast thou not signed a decree, that every man that shall ask a petition of any God or man within thirty days, save of thee, O king, shall be cast into the den of lions? The king answered and said, The thing is true, according to the law of the Medes and Persians, which altereth not.
[AD 420] Jerome on Daniel 6:12
Verse 12. "'Hast thou not ordained, O king, that any man who makes a request of any other person besides thee, whether god or man, shall be thrown into the lion-pit?' The king answered them, saying..." They do not mention Daniel's name, so that when the king has made a general answer as to the order he gave, he may then be bound by his own word, and not deal with Daniel in any other fashion than he has stated.

"'What you have said is true, according to the decree of the Medes and Persians, which it is not lawful to violate.'" We repeatedly take note of every passage which speaks of the kingdom of the Medes and Persians, so that we may dispose of the knotty problem of why Daniel speaks of the kingdom in one place as being under Darius, and in another as being under Cyrus.