Revelation 7:9, 13-14

After the vision of these things I looked, and there was a great number of people, so many that no one could count them. They were from every nation, tribe, people, and language of the earth. They were all standing before the throne and before the Lamb, wearing white robes and holding palm branches in their hands.

Then one of the elders asked me, “Who are these people dressed in white robes? Where did they come from?” I answered, “You know, sir.” And the elder said to me, “These are the people who have come out of the great distress. They have washed their robes and made them white in the blood of the Lamb.