Daniel 6:12
Then they came near, and spake before the king concerning the king’s decree; Hast thou not signed a decree, that every man that shall ask a petition of any God or man within thirty days, save of thee, 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 altereth not.
Cross-reference
Daniel 6:8 records the decree's establishment; here it is enforced against Daniel. Direct narrative cause and effect.
Daniel 3:8-12 similarly has officials accusing Shadrach, Meshach, and Abednego of disobeying a royal decree about worship.
Daniel 2:13 records a royal decree threatening Daniel's life, similar to the death decree he faces in this chapter.
Daniel 3:10 involves a decree forcing worship of an idol; here a decree forbids prayer to God. Both test loyalty.
Esther 1:19 illustrates the irrevocable nature of Persian decrees, explaining why the king could not revoke this one.
Esther 8:8 reiterates that a Persian decree sealed by the king cannot be revoked, echoing the legal reality here.
Esther 3:12 shows another Persian decree sealed with the king's signet, leading to persecution of God's people.