Rev 1:3 is one of the seven benedictions of the book of revelation - each one is directed to a specific group of people in the Christian era:
- Rev 1:3 - Blessed is the one who reads aloud the words of this prophecy, and blessed are those who hear and obey what is written in it, because the time is near.
- Rev 14:13 - And I heard a voice from heaven telling me to write, “Blessed are the dead—those who die in the Lord from this moment on.” “Yes,” says the Spirit, “they will rest from their labors, for their deeds will follow them.”
- Rev 16:15 - “Behold, I am coming like a thief. Blessed is the one who remains awake and clothed, so that he will not go naked and let his shame be exposed.”
- Rev 19:9 - Then the angel told me to write, “Blessed are those who are invited to the marriage supper of the Lamb.” And he said to me, “These are the true words of God.”
- Rev 20:6 - Blessed and holy are those who share in the first resurrection! The second death has no power over them, but they will be priests of God and of Christ, and will reign with Him for a thousand years.
- Rev 22:7 - “Behold, I am coming soon. Blessed is the one who keeps the words of prophecy in this book.”
- Rev 22:14 - Blessed are those who wash their robes, so that they may have the right to the tree of life and may enter the city by its gates.
While each of these blessings is pronounced on specific groups of people, a moment's reflection will reveal that each is different description of the faithful group of Christians at any period in Christian history as a comparison with other NT statements is easy to show.
A special note about NT culture - very few of the early church members were literate and thus, at church gatherings, someone who could read would stand and read part of the Bible to those who could not understand. (I note that in many churches today, this habit has continued despite the generally much higher literacy rate.)
Thus, Rev 1:3 is a general blessing on anyone who reads the prophecy of John the Revelator. In view of the promises of Ps 119:105, 2 Tim 3:16 and many more, the reading of God's word always attracts a blessing from God.
Note the comments of Matthew Henry -
1:1-3 This book is the Revelation of Jesus Christ; the whole Bible is
so; for all revelation comes through Christ, and all relates to him.
Its principal subject is to discover the purposes of God concerning
the affairs of the church, and of the nations as connected therewith,
to the end of the world. These events would surely come to pass; and
they would begin to come to pass very shortly. Though Christ is
himself God, and has light and life in himself, yet, as Mediator
between God and man, he receives instructions from the Father. To him
we owe the knowledge of what we are to expect from God, and what he
expects from us. The subject of this revelation was, the things that
must shortly come to pass. On all who read or hear the words of the
prophecy, a blessing is pronounced. Those are well employed who search
the Bible. It is not enough that we read and hear, but we must keep
the things that are written, in our memories, in our minds, in our
affections, and in practice, and we shall be blessed in the deed. Even
the mysteries and difficulties of this book are united with
discoveries of God, suited to impress the mind with awe, and to purify
the soul of the reader, though he may not discern the prophetic
meaning. No part of Scripture more fully states the gospel, and warns
against the evil of sin.