'Thief' in the Bible

Be mindful, therefore, of the lessons you have received and heard. Continually lay them to heart, and repent. If, however, you fail to rouse yourself and keep awake, I shall come upon you suddenly like a thief, and you will certainly not know the hour at which I shall come to judge you.

("I am coming like a thief. Blessed is the man who keeps awake and guards his raiment for fear he walk about ill-clad, and his uncomeliness become manifest.")