Heavenly agencies have to contend with hindrances before the purpose of God is fulfilled in its time. The king of Persia was controlled by the highest of all evil angels. He refused, as did Pharaoh, to obey the word of the Lord. Gabriel declared, He [Satan] withstood me twenty-one days by his representations against the Jews. But Michael came to his help, and then he remained with the kings of Persia, holding the powers in check, giving right counsel against evil counsel.—The S.D.A. Bible Commentary 4:1173. TA 144.1
[Cyrus] the [Persian] monarch had resisted the impressions of the Spirit of God during the three weeks while Daniel was fasting and praying, but Heaven's Prince, the archangel, Michael, was sent to turn the heart of the stubborn king to take some decided action to answer the prayer of Daniel.—The Review and Herald, February 8, 1881. TA 144.2
No less a personage than the Son of God appeared to Daniel. This description is similar to that given by John when Christ was revealed to him upon the Isle of Patmos. TA 144.3
Our Lord now comes with another heavenly messenger to teach Daniel what would take place in the latter days.—The Review and Herald, February 8, 1881. TA 144.4
Daniel ... could not look upon the angel's face, and he had no strength; it was all gone. So the angel came to him and set him upon his knees. He could not behold him then. And then the angel came to him with the appearance of a man. Then he could bear the sight.—Manuscript Releases 2:348. TA 144.5
The victory was finally gained, and the forces of the enemy were held in check all the days of Cyrus, who reigned for seven years, and all the days of his son Cambyses, who reigned about seven years and a half.—The Review and Herald, December 5, 1907. TA 145.1