Daniel 6:15-21
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.
The same men who orchestrated the action against Daniel now have the temerity to go to the king and remind him that no law can be changed which is made by the Medes and Persians.  They knew the king was working very hard to try and save Daniel from the penalty of death decreed in the 30 day law.  These evil men who plotted against Daniel thought that they now had Daniel where they wanted him and that soon they will be rid of him for good.  The problem with evil is that it is so blinded that it projects its goals without the very thought of an intervention by God.
Daniel 6:16
Then the king commanded, and they brought Daniel, and cast him into the den of lions. Now the king spake and said unto Daniel, Thy God whom thou servest continually, he will deliver thee.
The king did not have any recourse but to obey the very law that he signed and approved.  The king then went and summoned Daniel and had him cast into the den of lions but the king had more insight than the men who plotted against Daniel.  The king acknowledges the God of Daniel, that He is able to deliver him from the lion’s den.  The king would have definitely known this because Daniel would have exuded a great testimony for God in front of the king in his daily activities.  The king was hopeful and knew that Daniel had a great relationship with God and therefore knew that Daniel would be delivered from the jaws of death.  The king was wiser than his counselors.
Daniel 6:17
And a stone was brought, and laid upon the mouth of the den; and the king sealed it with his own signet, and with the signet of his lords; that the purpose might not be changed concerning Daniel.
This could have been a pit which was dug out of the ground or hewn out of rock to keep the lions at bay so no one would accidentally be attacked by the lions.  This rock that sealed the den would have been a large rock and very heavy to keep the lions from escaping.  Once the stone was set over the opening, then a royal seal was placed on it along with the seal of the lords.  This was done so that people would know that what was happening here was approved by the king and other leaders.  Anyone approaching would know that the purpose of this event was to punish Daniel for breaking the law of petitioning God instead of the king. 
Matthew 27:60 (KJV)   And laid it in his own new tomb, which he had hewn out in the rock: and he rolled a great stone to the door of the sepulchre, and departed.
Matthew 27:66 (KJV)   So they went, and made the sepulchre sure, sealing the stone, and setting a watch.
What we have here in Daniel was a prophetic event which would be repeated at the time of the crucifixion of the Lord Jesus Christ.  Once He had died, he was laid in the tomb of Joseph of Arimathea.  A very heavy stone was also laid in front of the tomb and then a seal was placed on the stone which would have warned anyone to stay away from that site.  They feared that Jesus’ claim of being resurrected would come to pass or that His disciples would steal the body by night and just claim He resurrected.
Daniel 6:18
Then the king went to his palace, and passed the night fasting: neither were instruments of musick brought before him: and his sleep went from him.
Once the stone was sealed and Daniel was inside the den, the king then departed to his palace but tonight was going to be much different than other nights.  Tonight the king was sullen in his mood.  He did not even eat anything and normally musical instruments were played before him but not tonight.  He did not even get any sleep which means it was probably a long night for him knowing what had happened and how he was used by these men because of his own vanity.  His mind was strictly upon the events of the day concerning Daniel.
Daniel 6:19
Then the king arose very early in the morning, and went in haste unto the den of lions.
The king could probably not wait any longer.  Once the day started to dawn he got his chariot driver to take him to the den of lions.  The den was probably not too close to the palace but some distance away so he went in haste, very quickly, to the den to see if Daniel had survived the night.  He showed how much care he had for Daniel because normally a king would not show themselves with this much concern but Daniel was probably his most trusted counselor.
Daniel 6:20
And when he came to the den, he cried with a lamentable voice unto Daniel: and the king spake and said to Daniel, O Daniel, servant of the living God, is thy God, whom thou servest continually, able to deliver thee from the lions?
Then the king finally arrived at the lion’s den and with a voice that was lamentable, that is, in distress, called out to Daniel.  At this point the king was not acting too royally as he made his way to the den.  Then the king makes a nice verbal testimony about God calling Him the “living God.”  This would be in contrast to the false stone gods of the Medes and Persians.  He then bellows out the question that he hoped all night he would get an answer to.  It seems the king’s faith ran a little dry.  In one his earlier statements he knew that the God that Daniel served could deliver him from the lions but here he asks the question if God was able to deliver him from the lions? 
Daniel 6:21
Then said Daniel unto the king, O king, live for ever.
Then the king hears the voice of Daniel and no doubt had become joyful since his most trusted counselor was still alive.  Daniel greets the king with a normal greeting and does not show any contempt toward the king and that is because he knew that it was not the king that orchestrated this affair but his jealous advisers and counselors.