Revelation 1:10; Revelation 4:1-2

10 I was in the Spirit on the Lord's day, and I heard behind me a loud voice like the sound of a trumpet,

1 After these things I looked, and behold, a door standing open in heaven, and the first voice which I had heard, like the sound of a trumpet speaking with me, said, "Come up here, and I will show you what must take place after these things."

2 Immediately I was in the Spirit; and behold, a throne was standing in heaven, and One sitting on the throne.