The Holy Bible, Revelation 8:1
1 And when he had opened the seventh seal, there was silence in heaven about the space of half an hour.
The Doctrine and Covenants, Section 38:11-12
11 For all flesh is corrupted before me; and the powers of darkness prevail upon the earth, among the children of men, in the presence of all the hosts of heaven—
12 Which causeth silence to reign, and all eternity is pained, and the angels are waiting the great command to reap down the earth, to gather the tares that they may be burned; and, behold, the enemy is combined.
The Doctrine and Covenants, Section 88:92-95
92 And angels shall fly through the midst of heaven, crying with a loud voice, sounding the trump of God, saying: Prepare ye, prepare ye, O inhabitants of the earth; for the judgment of our God is come. Behold, and lo, the Bridegroom cometh; go ye out to meet him.
93 And immediately there shall appear a great sign in heaven, and all people shall see it together.
94 And another angel shall sound his trump, saying: That great church, the mother of abominations… is ready to be burned. And he shall sound his trump both long and loud, and all nations shall hear it.
95 And there shall be silence in heaven for the space of half an hour; and immediately after shall the curtain of heaven be unfolded, as a scroll is unfolded after it is rolled up, and the face of the Lord shall be unveiled;
Journal of Discourses, Orson Pratt 16:43
“Immediately after the sounding of this trump, there will be silence in heaven for the space of half an hour.” Whether the half hour here spoken of is according to our reckoning–thirty minutes, or whether it be according to the reckoning of the Lord we do not know. We know that the word hour is used in some portions of the Scriptures to represent quite a lengthy period of time. For instance, we, the Latter-day Saints, are living in the eleventh hour, that is in the eleventh period of time; and for aught we know the half hour during which silence is to prevail in heaven may be quite an extensive period of time. During the period of silence all things are perfectly still; no angels flying during that half hour; no trumpets sounding; no noise in the heavens above; but immediately after this great silence the curtain of heaven shall be unfolded as a scroll is unfolded. School children, who are in the habit of seeing maps hung up on the wall, know that they have rollers upon which they are rolled up, and that to expose the face of the maps they are let down. So will the curtain of heaven be unrolled so that the people may gaze upon those celestial beings who will make their appearance in the clouds. The face of the Lord will be unveiled, and those who are alive will be quickened, and they will be caught up; and the Saints who are in their graves, will come forth and be caught up, together with those who are quickened, and they will be taken into the heavens into the midst of those celestial beings who will make their appearance at that time. These are the ones who are the firstfruits, that is, the firstfruits at the time of his coming.
Journal of Discourses, Orson Pratt 8:10
After all nations have heard the proclamation, there will be silence in the heavens, and I do not know but on the earth too; for the people will doubtless be overpowered with astonishment to see an angel, the sound of whose trump shall pierce the ears of all living. After this, I say, there will be silence in heaven for half-an-hour.