Verse 19:[1] Write (Rev. 1:12, etc.) the things which thou hast seen, (Rev. 2:1, etc.) and the things which are, (Rev. 4:1, etc.) and the things which shall be hereafter…
[Write, therefore (because thou seest me, so powerful [Grotius, thus Cotterius], endowed with authority; for I administered, and am going to administer, these things, and am able to reveal them to thee [Cotterius]) the things which thou hast seen[2] (that is, things past [Pareus, Durham], from the beginning of the Gospel; that is, the history of the Gospel from its rise and victories unto this time [Durham]: or, what things I have shown thee [Ribera], either the entire revelation attested in this Book; or those things which immediately preceded in this very chapter, which likewise belongs to me [Cluverus]: Others: which thou seest: An Hebraic enallage of tense [Piscator]: That is to say, First write this very vision, then thou art going to write the other things also [Grotius]: Which thou hast seen, narrated in this first chapter [Menochius], the Vision of the seven lamps, and of the seven stars [Hammond]: But a comparison with verse 11 prevents this from being referred to that particular Vision, in which verse He says in the singular number, What thing thou seest, write, etc.; but here in the plural number, what things thou hast seen [Durham]), and the things which (or, then the things which [Piscator]) are (that is, what things are now happening in the Church [Menochius, Tirinus, Ribera, Lapide]; the present state of the Churches throughout Asia [Grotius, Durham], under which others are also understood [Durham]: This is written in Revelation 2 and 3 [Grotius, Durham]), and the things which are necessary to be done (or, are going to be [Beza, Piscator]) thereafter] That is, what things are written in chapter 4 and thereafter (Grotius, similarly Piscator): or, the state of the Church and the future of the world (Piscator, similarly Durham), unto the second coming of Christ (Durham). The division and matter of the Apocalypse is here clearly revealed (Cluverus, similarly Durham), matters Past, Present, and Future (Cocceius, Cluverus, Durham). He had said, write what thing thou seest[3] (Brightman), and here, what things thou hast seen (Hammond). He now relates to what that was pertaining, namely, to things both Present and Future (Brightman, similarly Hammond). If it has regard to this Vision only, it relates that both the present and future state of those Churches are described in it: if, however, it be extended to the rest of the prophecy, it relates that both the present and future dispensations of Christ toward His Church are contained in the following visions; which Church He permits to be afflicted for a time, and He rewards it, while it perseveres. Now, these words clearly teach that this vision, proper to the seven Churches, is of matters both present and future; and that, in the Epistles, to which the parts of this vision are accommodated according to the various condition of each, predictions are found concerning future things. The observation of which small matter opened the way to me to understand (as I believe) the particular Epistles: which I maintain to be the judgment of the pious (Brightman). But the foundation of this is very weak. For, if, as he maintained, it be there asserted that the same matters were both present and future, it would have been necessary to have said, ἅ καὶ εἰσι καὶ μέλλει γίνεσθαι, what things both were and were going to be. Now, however, the phrase is far different, what things thou hast seen, καὶ ἅ εἰσι, καὶ ἃ μέλλει, that is, both what things were, and what things were going to be, or perhaps, and what things were, etc., which is clearly a distribution of the Visions with respect to the matter of them into two classes, one of which was the matter then present, the other of which was the matter about to be not long afterwards: however, it does not at all pertain to the distribution of those fulfillment, that these visions were fulfilled twice, once at that time, again after many ages, which is a crass error (Hammond).
Write the things which thou hast seen; either the things which thou hast seen from the beginning of the gospel; for John, Matthew 4:21, was a companion of Christ from the time presently following his baptism and temptations: or, the vision of me which thou hast now had; which I judge most probably the sense, not understanding why our Lord should set John to write what (though they were not yet written, yet) Christ knew should be written in another book by John himself, namely, in his Gospel, and by Matthew, Mark, and Luke, in their histories of the Gospel, and in the Acts of the Apostles; especially considering they were to be written plainly, so as he who runs may read them; and what John was to write here, was to be written enigmatically, and darkly represented in visions: and it is against reason to think the same things should be first revealed plainly, and then more darkly, and both by direction from God. And the things which are; the present affairs of the church; we have the history till Paul was carried prisoner to Rome, (which was about the sixtieth year after Christ,) in the Acts of the apostles; so that I conceive the farthest that John looked back was but thirty-five years; for he was in Patmos about the year AD 93, and is conceived to have written this book, AD 96. Hence the matter of the Revelation is easily concluded: 1. The things which were the present affairs of the church, AD 96, or looking back only to AD 60, which things are supposed to be written by John, in Revelation 2:3. And the things which shall be hereafter; to the end of the world, under the reign of the dragon, (the pagan Roman empire,) and the reign of antichrist, or the beast, for one thousand two hundred and sixty years, and from thence until Christ shall come to judgment.
[1] Greek: γράψον ἃ εἶδες, καὶ ἅ εἰσι, καὶ ἃ μέλλει γίνεσθαι μετὰ ταῦτα.
[2] Greek: ἃ εἶδες, in the aorist tense.
[3] Verse 11.
Dr. Dilday's Sermon: "Directions for the Interpretation of the Apocalypse, Part 1"
https://www.sermonaudio.com/sermoninfo.asp?SID=111101632516
1) Introduction
2) Analysis
a) Context
b) Verse 19
i) “The things which thou hast seen”
ii) “And the things which are”
iii) “And the things which shall be hereafter”
iv) Reflections on this outline
3) Compendium of interpretive lessons
a) Revelation as revelation
b) The main subject: events which must shortly come to pass
c) The apocalyptic scene
It would be easy to read over this verse, taking little notice; but it is quite important. We are not left to our own speculations in outlining this difficult book. Jesus Christ, the Prophet of the Church par excellence, provides an outline. John is to write the things which he has seen (the vision of Christ in Revelation 1), the things which are (the present condition of the seven churches in Asia Minor, Revelation 2 and 3), and the things after those (the vision of things from John's time to the end of the world (Revelation 4-22). It is not yet a detailed outline, but it is an infallible starting point.
William Tong (for Matthew Henry): 'The condescending goodness of the Lord Jesus to his disciple: He laid his hand upon him, Revelation 1:17. He raised him up; he did not plead against him with his great power, but he put strength into him, he spoke kind words to him. [1.] Words of comfort and encouragement: Fear not.... [2.] Words of instruction, telling him particularly who he was that thus appeared to him. And here he acquaints him... With his will and pleasure: Write the things which thou hast seen, and the things which are, and which shall be hereafter.'