Esther 1:19 If it please the king, let a royal commandment go from him, and let it be written among the laws of the Persians and the Medes, so that it cannot be altered, that Vashti may never again come before King Ahasuerus; and let the king give her royal estate to another who is better than she. (See NAS NIV)
Daniel 6:8 Now, O king, establish the decree, and sign the writing, that it not be changed, according to the law of the Medes and Persians, which doesn't alter. (See NIV)
Daniel 6:12 Then they came near, and spoke before the king concerning the king's decree: Haven't you signed an decree, that every man who shall make petition to any god or man within thirty days, except to you, O king, shall be cast into the den of lions? The king answered, The thing is true, according to the law of the Medes and Persians, which doesn't alter. (See NIV)