Revelation 3:3; Revelation 16:15

3 Remember therefore how thou hast received and heard , and hold fast , and repent . If therefore thou shalt not watch , I will come on thee as a thief, and thou shalt not know what hour I will come upon thee.
15 Behold , I come as a thief. Blessed is he that watcheth , and keepeth his garments, lest he walk naked, and they see his shame.