On I Am Daniel
AN Poet explanation.

If King Darius was speaking thus it meant that he was thinking of poor Daniel in that cave and it could very well have come from him speaking to hisself to his inner conscience and so the reader can decide to read this verse as if KING Darius speaks it first…

Darius Speaking?

My heart so troubled earlier and earnestly seeking deliverance is now at rest and I can be blessed in every circumstance because I kept the faith of GOD a test but not from him to us this test is testing no one least of all this Daniel. The lions do not roar.

Or Daniel Thinking?

And if the speaker now is DANIEL then self evidence assured
He was wondering out loud and marveling at his creator action that his creator would deliver him.