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.
Berean Study Bible (BSB) - Revelation 4:1 >After this I looked and saw a door standing open in heaven. And the voice I had previously heard speak to me like a trumpet was saying, “Come up here, and I will show you what must happen after these things.”