Daniel 6:8-12 NKJV
Now, O king, establish the decree and sign the writing, so that it cannot be changed, according to the law of the Medes and Persians, which does not alter.” Therefore King Darius signed the written decree.
Now when Daniel knew that the writing was signed, he went home. And in his upper room, with his windows open toward Jerusalem, he knelt down on his knees three times that day, and prayed and gave thanks before his God, as was his custom since early days.
Then these men assembled and found Daniel praying and making supplication before his God. And they went before the king, and spoke concerning the king’s decree: “Have you not signed a decree that every man who petitions any god or man within thirty days, except you, 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 does not alter.”
NKJV: New King James Version