Daniel 6:15
Then these men assembled unto the king, and said unto the king, Know, O king, that the law of the Medes and Persians is, That no decree nor statute which the king establisheth may be changed.
Cross-reference
Daniel 6:8
Historical context
In Daniel 6:8, the same principle of an unchangeable law is first proposed — the conspirators set the trap using the Medo-Persian custom.
Daniel 6:12
Parallel
In Daniel 6:12, the conspirators confront the king about his decree; verse 15 then presses him on its irrevocability, escalating the pressure.
Esther 8:8
Historical context
In Esther 8:8, the same Persian legal rule appears: a royal decree sealed with the ring cannot be revoked — mirroring the dilemma here.
Esther 3:12
Historical context
In Esther 3:12, Haman's decree to destroy the Jews is sealed irrevocably — a similar use of irreversible royal law against God's people.