This is Ellen White's commentary on Revelation
15:2-5

Revelation 15:2-5 (KJV) And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of God.
And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints.
Who shall not fear thee, O Lord, and glorify thy name? for thou only art holy: for all nations shall come and worship before thee; for thy judgments are made manifest.
And after that I looked, and, behold, the temple of the tabernacle of the testimony in heaven was opened:

This quote is by Ellen White
Acts of Apostle
Page 589
John sees a perfect mix

John saw the marcy, the tenderness, and the love of God blending with His holiness, justices, and power,. He saw diners find a Father in Him in whom there sins had made them afraid. And looking beyond the culminationof the great conflict he beheld upon Zion"them that had gotten the victory....stand on the sea of bless, having the harps of God," and singing" the song of Moses"and the Lamb (Revelation 15:2,3).


This is another quote by Ellen White
Patriarchs and Prophets
Page 357
Understanding the Sanctuary a Key

Moses made the earthly sanctuary "according to the fashion that he had seen." Paul declares that " tabernacle and all the vessels of the ministry," when completed, were " the pattern of things in heavens" (Acts7:44, Hebrews9:21,23). And John said he saw the sanctuary in heaven. The sanctuary, in which Jesus ministers in our behalf in the great orignal, of which the sanctuary built by Moses was a copy.