Behold, I come quickly - See the notes on Revelation 1:3. The words used here are undoubtedly the words of the Redeemer, although they are apparently repeated by the angel. The meaning is, that they were used by the angel as the words of the Redeemer. See Revelation 22:12, Revelation 22:20.
Blessed is he that keepeth the sayings of the prophecy of this book - That receives them as a divine communication; that makes use of them to comfort himself in the days of darkness, persecution, and trial; and that is obedient to the precepts here enjoined. See the notes on Revelation 1:3.

Behold, I come quickly,.... These are the words not of the angel, but of Christ, as is manifest from Revelation 22:12 and which are to be understood not of Christ's coming in his power to destroy Jerusalem, for this was past when John had these visions, and wrote this book; but of the second and personal coming of Christ to judgment, as is clear from Revelation 22:12 which though it will not be sooner than the time appointed, yet will be as soon as that time is come, and sooner than is generally expected by men. The Ethiopic version adds, "as a thief", as in Revelation 16:15 and because the second coming of Christ is an affair of the utmost moment, and will be attended with events of the greatest consequence and importance, in which the visions of this book issue, a "behold" is prefixed to it, as a note of attention and admiration:
blessed is he that keepeth the sayings of the prophecy of this book; this book is a prophecy of things to come, and therefore cannot refer to the times of Jerusalem's destruction, which some interpreters make it chiefly to concern, for then it would be a narrative of things past; the sayings of it are the things contained in it; to keep these sayings is to read them with observation, to take notice of the accomplishment of them, so far as it has taken place, to keep them in mind and memory, to meditate upon them, and through the grace of God to steer the life and conversation according to the instructions, directions, and cautions here given; and such are blessed in life, and will be in death; they will die in the Lord, share in the first resurrection, and enter through the gates into the city.

"And" is omitted in Coptic and ANDREAS with English Version, but is inserted by A, B, Vulgate and Syriac.
blessed-- (Revelation 1:3).

Behold, I come quickly - Saith our Lord himself, to accomplish these things. Happy is he that keepeth - Without adding or diminishing, Revelation 22:18-19, the words of this book.