Matthew 24:50
the lord of that slave shall come in a day when he does not look for him and in an hour that he is not aware of
Matthew 24:42-44
Watch therefore, for ye know not what hour your Lord doth come.
1 Thessalonians 5:2-3
For ye know well that the day of the Lord shall come as a thief in the night.
Revelation 3:3
Remember, therefore, of that which thou hast received and heard and hold to it and repent. If therefore thou shalt not watch, I will come to thee as a thief, and thou shalt not know what hour I will come upon thee.
Proverbs 29:1
He that being often reproved hardens his neck shall suddenly be destroyed and that without remedy.