Revelation 7:14-15

14I replied, ‘You surely know who they are, sir.’ He said to me, ‘They are the people who have had a time of very bad trouble. Now they have come out of that. They have washed their clothes in the blood of the Lamb. Now their clothes are white and clean.

15Because of that, they are now standing in front of God's throne. They serve God in his house all the time, day and night. And God will keep them safe because he is with them.