Then the king went to his palace, and passed the night fasting: neither were instruments of music brought before him: and his sleep went from him.
All Commentaries on Daniel 6:18 Go To Daniel 6
Aquinas Study Bible
AD 2017
He sealed with his ring the rock by which the opening of the pit was shut up, so that the enemies of Daniel might not make any attempt to harm him. For he had entrusted him to the power of God, and although not worried about lions, he was fearful of men. He also sealed it with the ring of his nobles, in order to avoid all ground for suspicion so far as they were concerned. (St. Jerome)