Revelation 6:11

6:11 Each of them was given a long white robe and they were told to rest for a little longer, until the full number was reached of both their fellow servants and their brothers who were going to be killed just as they had been.

Revelation 7:9

7:9 After these things I looked, and here was an enormous crowd that no one could count, made up of persons from every nation, tribe, people, and language, standing before the throne and before the Lamb dressed in long white robes, and with palm branches in their hands.