Mark 13:32-37 (KJV)
32 But of that day and that hour knoweth no man, no, not the angels which are in heaven, neither the Son, but the Father.
33 Take ye heed, watch and pray: for ye know not when the time is.
34 For the Son of Man is as a man taking a far journey, who left his house, and gave authority to his servants, and to every man his work, and commanded the porter to watch.
35 Watch ye therefore: for ye know not when the master of the house cometh, at even, or at midnight, or at the cockcrowing, or in the morning:
36 Lest coming suddenly he find you sleeping.
37 And what I say unto you I say unto all, Watch.