Daniel 6:12

6:12 So they approached the king and said to him, “Did you not issue an edict to the effect that for the next thirty days anyone who prays to any god or human other than to you, O king, would be thrown into a den of lions?” The king replied, “That is correct, according to the law of the Medes and Persians, which cannot be changed.”

Daniel 6:15

6:15 Then those men came by collusion to the king and said to him, “Recall, O king, that it is a law of the Medes and Persians that no edict or decree that the king issues can be changed.”

Esther 1:19

1:19 If the king is so inclined, let a royal edict go forth from him, and let it be written in the laws of Persia and Media that cannot be repealed, that Vashti may not come into the presence of King Ahasuerus, and let the king convey her royalty to another who is more deserving than she.

Esther 8:3

8:3 Then Esther again spoke with the king, falling at his feet. She wept and begged him for mercy, that he might nullify the evil of Haman the Agagite which he had intended against the Jews.