Matthew 24:50
that servant's master will come in a day when he looketh not for him: and in a hour that he is not aware of,
Matthew 24:42-44
Wake, therefore, because ye know not what hour your master will come.
1 Thessalonians 5:2-3
for ye your selves know perfectly, that the day of the Lord shall come even as a thief in the night.
Revelation 3:3
Remember, therefore, how thou hast received and heard, and hold fast, and repent. If you shalt not watch, I will come on you as a thief, and thou shalt not know what hour I will come upon thee.
Proverbs 29:1
He that is stiff necked and will not be reformed, shall suddenly be destroyed without any help.