Mark 13:33-37

Take ye heed, watch and pray: for ye know not when the time is. It is as when a man, sojourning in another country, having left his house, and given authority to his servants, to each one his work, commanded also the porter to watch. Watch therefore: for ye know not when the lord of the house cometh, whether at even, or at midnight, or at cockcrowing, or in the morning; lest coming suddenly he find you sleeping. And what I say unto you I say unto all, Watch.