Daniel 6:10, 15

And when Daniel knew that the writing was signed, he went into his house (now his windows were open in his chamber toward Jerusalem); and he kneeled upon his knees three times a day, and prayed, and gave thanks before his God, as he did aforetime.

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.