In Revelation chapter 20, the Bible mentions two resurrections surrounding the millennium, or thousand year reign of Christ on this earth. The first resurrection is at the beginning of the millennium. The other resurrection is at the end of the millennium. The martyrs from the great tribulation were included in the first resurrection, along with the Old Testament believers (Daniel 12:1-4).
The souls of the Old Testament saints are already with the Lord. In the resurrection at the beginning of the millennium, they shall receive their glorified bodies (Rev. 20:4-6). The martyrs of the great tribulation are included in that resurrection. The martyrs reward is to rule and reign with Christ during the millennium.
All these things happen according to Daniel's prophecy, at "the time of the end" (Daniel 12:7). The end time includes the great tribulation, the second coming, the millennium, both resurrections, as well as the great white throne judgment (Rev. 19-20).
All these things follow the order of First Corinthians 15:20-26. There is a threefold order. First, there is the resurrection of Christ. Second, there is the coming of Christ for the rapture of the church, "those who are Christ's at His coming" (v. 23). Third, there is the end time, which Daniel prophesied. "Then comes the end" (v. 24).
