revelation Chapter 7

Then I saw another angel coming up from the east, having the seal of the living God. He called out in a loud voice to the four angels who had been given power to harm the land and the sea: (Revelation 7:2)

"Do not harm the land or the sea or the trees until we put a seal on the foreheads of the servants of our God." (Revelation 7:3)

Then I heard the number of those who were sealed: 144,000 from all the tribes of Israel. (Revelation 7:4)

the angels put a seal on the foreheads of the servants of God, who will be blessed by angels during the tribulation.

The 144,000 are also the ones chosen at the beginning of the Christ’s second coming.

After this I looked and there before me was a great multitude that no one could count, from every nation, tribe, people and language, standing before the throne and in front of the Lamb. They were wearing white robes and were holding palm branches in their hands. (Revelation 7:9) 

And one of the elders said, "These are they who have come out of the great tribulation; they have washed their robes and made them white in the blood of the Lamb. (Revelation 7:14) 

Blessed are those who have washed their robes. 

They can go to the tree of life, or enter the new Jerusalem.

Therefore, "they are before the throne of God and serve him day and night in his temple; and he who sits on the throne will spread his tent over them. (Revelation 7:15)

Never again will they hunger; never again will they thirst. The sun will not beat upon them, nor any scorching heat. (Revelation 7:16)

For the Lamb at the center of the throne will be their shepherd; he will lead them to springs of living water. And God will wipe away every tear from their eyes." (Revelation 7:17)

The “springs of living water” is a constant source of wisdom, which nourishes life and can ultimately lead to eternal life.

And he will send his angels and gather his elect from the four winds, from The ends of the earth to the ends of the heavens. (Mark 13:27)