To the angel of the church in Philadelphia write:
These are the words of him who is holy and true, who holds the key of David. What he opens no one can shut, and what he shuts no one can open. 8 I know your deeds. See, I have placed before you an open door that no one can shut. I know that you have little strength, yet you have kept my word and have not denied my name. 9 I will make those who are of the synagogue of Satan, who claim to be Jews though they are not, but are liars—I will make them come and fall down at your feet and acknowledge that I have loved you. 10 Since you have kept my command to endure patiently, I will also keep you from the hour of trial that is going to come on the whole world to test the inhabitants of the earth. (Revelation 3:8-10)
Verse 10 of Revelation chapter 3 records an incredible promise by Jesus to the believers at Philadelphia that they will not have to go through “the hour of trial that is going to come on the whole world.” Obviously, this hour of trial is the horrible tribulation period that is picture in chapters 6-19 of Revelation. Because they had survived small tribulations, and had “kept my command to endure patiently” Jesus assured them with clear words that they would not have to go through the tribulation itself.