Commentaries:
Robertson's Word Pictures (NT)
Were loosed (eluqhsan). First aorist (ingressive) passive indicative of luw, "were let loose."
Which had been prepared (oi htoimasmenoi). Perfect passive articular participle of etoimazw, to make ready (etoimov), in a state of readiness prepared by God (Revelation 12:6; Revelation 16:12; Matthew 25:34).
For the hour and day and month and year (eiv thn wran kai hmeran kai mhna kai eniauton). For this use of eiv with htoimasmenon see II Timothy 2:21. All preparation over, the angels are waiting for the signal to begin.
That they should kill (ina apokteinwsin). The same idiom in verse Revelation 9:5 about the fifth trumpet, which brought torture. This one brings death.
Other Robertson's Word Pictures (NT) entries containing Revelation 9:15:
Revelation 9:14
Revelation 12:6
Revelation 16:12
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