John the Apostle
Revelation 6:10ESV·traditional attribution

They cried out with a loud voice, “O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?”

Matthew Henry Presbyterian @wholebiblehenry

In the remaining part of this chapter we have the opening of the fifth and the sixth seals. I. The fifth seal. Here is no mention made of any one who called the apostle to make his observation, probably because the decorum of the vision was to be observed, and each of the four living creatures had discharged its duty of a monitor before, or...

Commenting on Revelation 6:9-17

John Gill Reformed Baptist @doctorgill

And they cried with a loud voice,.... With great ardour and fervency, being very pressing and importunate; and which shows that they were awake, and not asleep, and that the soul does not sleep with the body in the grave, or is after the death of that in a state of insensibility and inactivity, as some imagine: saying, how long, O Lord, holy and true...

Jamieson-Fausset-Brown Reformed @jfbcommentary

How long--Greek, "Until when?" As in the parable the woman (symbol of the Church) cries day and night to the unjust judge for justice against her adversary who is always oppressing her (compare below, Rev 12:10); so the elect (not only on earth, but under Christ's covering, and in His presence in Paradise) cry day and night to God, who will assuredly, in His own...