"However, no one knows the day or hour when these things will happen, not even the angels in heaven or the Son himself. Only the Father knows.
And since you don't know when they will happen, stay alert and keep watch.
References for Mark 13:33
"The coming of the Son of Man can be compared with that of a man who left home to go on a trip. He gave each of his employees instructions about the work they were to do, and he told the gatekeeper to watch for his return.
So keep a sharp lookout! For you do not know when the homeowner will return -- at evening, midnight, early dawn, or late daybreak.
Don't let him find you sleeping when he arrives without warning.
What I say to you I say to everyone: Watch for his return!"