John the Apostle
Revelation 10:6BSB·traditional attribution

And he swore by Him who lives forever and ever, who created heaven and everything in it, the earth and everything in it, and the sea and everything in it: “There will be no more delay!

Matthew Henry Presbyterian @wholebiblehenry

Here we have an account of another vision the apostle was favoured with, between the sounding of the sixth trumpet and that of the seventh. And we observe, I. The person who was principally concerned in communicating this discovery to John - an angel from heaven, another mighty angel, who is so set forth as would induce one to think it could be no other...

Commenting on Revelation 10:1-7

John Gill Reformed Baptist @doctorgill

And sware by him that liveth for ever and ever,.... That is, by the living God, who is the true God: and is so described to distinguish him from idol gods, who have no life nor breath in them; and to assert the excellency and perfection of his nature, who has life in himself originally, and independently, is the fountain of life to all creatures...

Albert Barnes Presbyterian @notesbybarnes

Verse 6. And sware by him that liveth for ever and ever. By the everliving God: a form of an oath in extensive use now. The essential idea in such an oath is an appeal to God; a solemn reference to Him as a witness; an utterance in the presence of Him who is acquainted with the truth or falsehood of what is said, and...