Daniel 6:27 (ESV) .. “He delivers and rescues; he works signs and wonders in heaven and on earth, he who has saved Daniel from the power of the lions.”
The one who by his decree was being revered for a month as god (v. 7) now made a proclamation that all subjects of his nation (all the peoples, nations, and men of every language; cf. 3:4, 7; 4:1; 5:19; 7:14) must fear and reverence Daniel’s God. This was an amazing turnaround on Darius’ part! The reason for this, Darius wrote, is that Daniel’s God lives (He is the living God; cf. 6:20) whereas the gods of the Medes and Persians were dead idols. This God is eternal, His kingdom is indestructible (cf. 7:14), and He intervenes in people’s affairs and delivers those who trust Him. He works by miraculous power (signs and wonders; cf. 4:2–3) to perform His will, including the miraculous delivery of Daniel. Such a God is truly to be reverenced and worshiped. In spite of the opposition of the satraps and administrators, Daniel was honored and lived during the reigns of Darius and Cyrus.
Darius delivered two messages here. The first message was to those people who were servants of Darius. Let them beware of trying to manipulate the king; they will come to a bad end. The clean sweep made of not only the conspirators themselves but also their families was typical. It was summary vengeance indeed.
The second message was to the subjects of Darius. Who but the true and living God could have preserved Daniel in the den? Let all of his subjects tremble before Daniel’s God; He is invincible and His kingdom is without measure or end.
As for Daniel himself, he was all that God had planned for the nation of Israel to be—a testimony to Gentiles everywhere of the wonder and ways of the true and living God. Israel had failed. It had sunken to the grossest idolatry. So God dismantled the kingdom and scattered the people. However, He never leaves Himself without a witness. During Israel’s seventy-year captivity in Babylon, God raised up Daniel and his three friends to bear powerful witness to God.
P. B. Bliss, in an old gospel hymn, summarized it thus:
Dare to be a Daniel!
Dare to stand alone!
Dare to have a purpose firm!
Dare to make it known.
 Pentecost, J. D. (1985). Daniel. In J. F. Walvoord & R. B. Zuck (Eds.), The Bible Knowledge Commentary: An Exposition of the Scriptures (Vol. 1, p. 1349). Wheaton, IL: Victor Books.  Phillips, J. (2009). Exploring the Book of Daniel: An Expository Commentary (Da 6:24–28). Kregel Publications; WORDsearch Corp.