Revelation 3:2-4

Be constantly alert, and strengthen the things that remain, which were about to die; for I have not found your deeds completed in the sight of My God. So remember what you have received and heard; and keep it, and repent. Then if you are not alert, I will come like a thief, and you will not know at what hour I will come to you. But you have a few people in Sardis who have not soiled their garments; and they will walk with Me in white, for they are worthy.