John the Apostle
Revelation 11:7ESV·traditional attribution

And when they have finished their testimony, the beast that rises from the bottomless pit will make war on them and conquer them and kill them,

Matthew Henry Presbyterian @wholebiblehenry

In this time of treading down, God has reserved to himself his faithful witnesses, who will not fail to attest the truth of his word and worship, and the excellency of his ways. Here observe, I. The number of these witnesses: it is but a small number and yet it is sufficient. 1. It is but small.

Commenting on Revelation 11:3-13

John Gill Reformed Baptist @doctorgill

And when they shall have finished their testimony,.... For Christ, his truths and ordinances; when they are about to finish it, and almost concluded it, even towards the close of the 1260 days or years, in which they must prophesy in sackcloth: or else their testimony and their prophesying may be considered as two distinct things, and the one be finished before the other; their...

Albert Barnes Presbyterian @notesbybarnes

Verse 7. And when they shall have finished their testimony. Professor Stuart renders this, "And whenever they shall have finished their testimony." The reference is undoubtedly to a period when they should have faithfully borne the testimony which they were appointed to bear. The word here rendered "shall have finished"-- τελεσωσι, from τελεω--means properly to end, to finish, to complete, to accomplish.