Revelation 20:6

Blessed and holy are those who have a part in the first resurrection. The second death has no power over them, but they will be priests of God and of Christ and will reign with him for a thousand years.

Blessed
Revelation 14:13 Then I heard a voice from heaven say, "Write: Blessed are the dead who die in the Lord from now on." "Yes," says the Spirit, "they will rest from their labor, for their deeds will follow them."

The second death
Revelation 2:11 "He who has an ear, let him hear what the Spirit says to the churches. He who overcomes will not be hurt at all by the second death."
Revelation 20:14 Then death and Hades were thrown into the lake of fire. The lake of fire is the second death.

but they will be priests
1 Peter 2:5 ... you also, like living stones, are being built into a spiritual house to be a holy priesthood, offering spiritual sacrifices acceptable to God through Jesus Christ.
Revelation 1:6 ... and has made us to be a kingdom and priests to serve his God and Father--to him be glory and power for ever and ever. Amen.

and will reign with him
Revelation 3:21 "To him who overcomes, I will give the right to sit with me on my throne, just as I overcame and sat down with my Father on his throne."
Revelation 5:10 "You have made them to be a kingdom and priests to serve our God, and they will reign on the earth."
Revelation 20:4 I saw thrones on which were seated those who had been given authority to judge. And I saw the souls of those who had been beheaded because of their testimony for Jesus and because of the word of God. They had not worshiped the beast or his image and had not received his mark on their foreheads or their hands. They came to life and reigned with Christ a thousand years.
Revelation 22:5 There will be no more night. They will not need the light of a lamp or the light of the sun, for the Lord God will give them light. And they will reign for ever and ever.

Scriptures taken from the Holy Bible, New International Version® NIV®, Copyright© 1973, 1978, 1984 by International Bible Society. Used by permission. All rights reserved worldwide.