The Holy Bible, Revelation 15:2

2 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.

The Holy Bible, Revelation 21:1-3

1 And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.

2 And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.

3 And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God.

The Holy Bible, Revelation 4:6

6 And before the throne there was a sea of glass like unto crystal: and in the midst of the throne, and round about the throne, were four beasts full of eyes before and behind.

The Doctrine and Covenants, Section 77:1

1 Q. What is the sea of glass spoken of by John, 4th chapter, and 6th verse of the Revelation? A. It is the earth, in its sanctified, immortal, and eternal state.

The Doctrine and Covenants, Section 88:16-29

Conference Report, George A. Smith, October 1942

Now tonight we are here in peace and quiet. The world is on fire. Everywhere peace has been taken from the earth, and the devil has been given power over his own dominion. God has said if we will honor Him and keep His commandments–if we will observe His laws He will fight our battles and destroy the wicked, and when the time comes He will come down in heaven–not from heaven–but He will bring heaven with Him–and this earth upon which we dwell, will be the celestial kingdom.

History of the Church, Joseph Smith 5:279

While at dinner, I remarked to my family and friends present, that when the earth was sanctified and became like a sea of glass, it would be one great urim and thummim, and the Saints could look in it and see as they are seen.

Journal of Discourses, Brigham Young, 14:19

By and by the Lord will purify the earth, and it will become pure and holy, like a sea of glass; then it will take its place in the rank of the celestial ones, and be recognized as celestial; but at the present time it is a dark, little speck in space.

Journal of Discourses, Brigham Young, 7:26

And this world, so benighted at present, and so lightly esteemed by infidels, as observed by brother Clements, when it becomes celestialized, it will be like the sun, and be prepared for the habitation of the Saints, and be brought back into the presence of the Father and the Son. It will not then be an opaque body as it now is, but it will be like the stars of the firmament, full of light and glory: it will be a body of light. John compared it, in its celestialized state, to a sea of glass.

Journal of Discourses, Brigham Young, 8:51

When shall we meet to part no more? Never, never; no, never. That is a curious idea, and I have not time to give full explanations. We shall go and come; and when we are in the eternity, we shall be on this earth, which will be brought into the immediate presence of the Father and the Son. We shall inhabit different mansions, and worlds will continue to be made, formed, and organized, and messengers from this earth will be sent to others. This earth will become a celestial body–be like a sea of glass, or like a Urim and Thummim; and when you wish to know anything, you can look in this earth and see all the eternities of God. We shall make our home here, and go on our missions as we do now, but at greater than railroad speed.

Journal of Discourses, Joseph F. Smith, 23:20

Things upon the earth, so far as they have not been perverted by wickedness, are typical of things in heaven. Heaven was the prototype of this beautiful creation when it came from the hand of the Creator, and was pronounced “good.”

Scriptural Teachings of the Prophet Joseph Smith :181

All beings who have bodies have power over those who have not. The devil has no power over us only as we permit him. The moment we revolt at anything which comes from God, the devil takes power. This earth will be rolled back into the presence of God, and crowned with celestial glory.