Revelation 4:1

"After this I looked, and, behold, a door was opened in heaven: and the first voice which I heard was as it were of a trumpet talking with me; which said, Come up hither, and I will shew thee things which must be hereafter."

Cross References (ranked by relevance)

Revelation 11:12 24

And they heard a great voice from heaven saying unto them, Come up hither. And they ascended up to heaven in a cloud; and their enemies beheld them.

Exodus 24:12 18

And the LORD said unto Moses, Come up to me into the mount, and be there: and I will give thee tables of stone, and a law, and commandments which I have written; that thou mayest teach them.

Revelation 1:19 13

Write the things which thou hast seen, and the things which are, and the things which shall be hereafter;

Revelation 1:10

I was in the Spirit on the Lord’s day, and heard behind me a great voice, as of a trumpet,

Mark 1:10

And straightway coming up out of the water, he saw the heavens opened, and the Spirit like a dove descending upon him:

Revelation 22:6

And he said unto me, These sayings are faithful and true: and the Lord God of the holy prophets sent his angel to shew unto his servants the things which must shortly be done.

Revelation 16:17

And the seventh angel poured out his vial into the air; and there came a great voice out of the temple of heaven, from the throne, saying, It is done.

John 16:13

Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.

Acts 7:56

And said, Behold, I see the heavens opened, and the Son of man standing on the right hand of God.

Luke 3:21

Now when all the people were baptized, it came to pass, that Jesus also being baptized, and praying, the heaven was opened,

Exodus 19:24

And the LORD said unto him, Away, get thee down, and thou shalt come up, thou, and Aaron with thee: but let not the priests and the people break through to come up unto the LORD, lest he break forth upon them.

Acts 10:11

And saw heaven opened, and a certain vessel descending unto him, as it had been a great sheet knit at the four corners, and let down to the earth:

Matthew 3:16

And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: