Bible Verses About Decrees: Of the Medes, irrevocable

Then the king, when he heard these words, was sore displeased, and set his heart on Daniel to deliver him; and he labored till the going down of the sun to rescue him.

Then these men assembled together unto the king, and said unto the king, Know, O king, that it is a law of the Medes and Persians, that no interdict nor statute which the king establisheth may be changed.