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.

Revelation 7:13

7:13 Then one of the elders asked me, “These dressed in long white robes – who are they and where have they come from?”