Revelation 1:1-3 (ESV Strong's)
1 The revelation of Jesus Christ, which God gave him to show to his servants the things that must soon take place. He made it known by sending his angel to his servant John, 2 who bore witness to the word of God and to the testimony of Jesus Christ, even to all that he saw. 3 Blessed is the one who reads aloud the words of this prophecy, and blessed are those who hear, and who keep what is written in it, for the time is near.
Jesus sends the Holy Spirit, His Angel, to John to show what will take place in the future. The Spirit bears witness to the word of God and to the testimony of Jesus Christ because He was the Spirit of Jesus. In the Church letters that follow we are told to listen to what the Spirit says. It is the Lord who speaks.
Blessed are those who hear and keep what is written in these letters that will follow.