'Thief' in the Bible

'Remember, then, how thou hast received, and heard, and be keeping, and reform: if, then, thou mayest not watch, I will come upon thee as a thief, and thou mayest not know what hour I will come upon thee.

lo, I do come as a thief; happy is he who is watching, and keeping his garments, that he may not walk naked, and they may see his unseemliness,' --