Bible Verses About Decrees: Of the Medes, irrevocable

Now when the king had heard these words, he was very much grieved, and in behalf of Daniel he set his heart to deliver him, and even till sunset he laboured to save him.

But those men perceiving the king's design, said to him: Know thou, O king, that the law of the Medes and Persians is, that no decree which the king hath made, may be altered.