"Finally these men said, 'We will never find any basis for charges against this man Daniel unless it has something to do with the law of his God.'" NIV translation
The enemy could not find anything to accuse Daniel of in his work so they decided they must go after him with his own faith. The same type of thing happens even today as we seek to follow after Jesus. There are those who seek to use our faith against us to accomplish what they want.
"So the administrators and the satraps went as a group to the king and said: 'O King Darius, live forever! The royal administrators, prefects, satraps, advisers and governors have all agreed that the king should issue an edict and enforce the decree that anyone who prays to any god or man during the next thirty days, except to you, O king, shall be thrown into the lions' den. Now, O king, issue the decree and put it in writing so that it cannot be altered - in accordance with the laws of the Medes and Persians, which cannot be repealed.' So King Darius put the decree in writing." NIV translation
King Darius was a "good" man but the rulers knew of his vanity. They played on that vanity by elevating him to the status of a god. The order was that anyone who prayed to anyone but the king for thirty days was to be killed by being thrown into the den of lions. As with any decree in the kingdom, once it was written and sealed it could not be repealed.
This passage is a reminder to all of us that pride can bring down the seemingly "good man". It was pride that brought about the fall of Lucifer and it is that same pride that is at the root of our sin.
"Now when Daniel learned that the decree had been published, he went home to his upstairs room where the windows opened toward Jerusalem. Three times a day he got down on his knees and prayed giving thanks to his God, just as he had done before." NIV translation
We see that he did not let the decree stop him from following the ways of God. It is interesting to note that, in the face of the prescribed penalty, Daniel did not pray for protection but instead gave thanks to God. He was not only a man of prayer but also a man of great faith and courage. We also see that he did not go out and disrespect the king by performing his prayers in the public square. He respected the king's authority but knew that ultimately all authority rested in God.