John the Apostle
Revelation 1:19BSB·traditional attribution

Therefore write down the things you have seen, the things that are, and the things that will happen after this.

Matthew Henry Presbyterian @wholebiblehenry

We have now come to that glorious vision which the apostle had of the Lord Jesus Christ, when he came to deliver this revelation to him, where observe, I. The account given of the person who was favoured with this vision. He describes himself, 1. By his present state and condition. He was the brother and companion of these churches in tribulation, and in the kingdom and patience of Christ.

Commenting on Revelation 1:9-20

John Gill Reformed Baptist @doctorgill

Write the things which thou hast seen,.... The Alexandrian copy and some others, and the Complutensian edition, read, "write therefore the things", &c. meaning what he had now seen, the vision of one like to the son of man, amidst the golden candlesticks, with seven stars in his right hand, and as above described; this was what he had seen Rev 1:12; for it does...

Albert Barnes Presbyterian @notesbybarnes

Verse 19. Write the things which thou hast seen. An account of the vision which thou hast had, . And the things which are. Give an account of those things which thou hast seen as designed to represent the condition of the seven churches.