Matthew 24:50
the lord of that bondman shall come in a day when he does not expect it, and in an hour he knows not of,
Matthew 24:42-44
Watch therefore, for ye know not in what hour your Lord comes.
1 Thessalonians 5:2-3
for ye know perfectly well yourselves, that the day of the Lord so comes as a thief by night.
Revelation 3:3
Remember therefore how thou hast received and heard, and keep it and repent. If therefore thou shalt not watch, I will come upon thee as a thief, and thou shalt not know at what hour I shall come upon thee.
Proverbs 29:1
He that being often reproved hardeneth his neck, shall suddenly be destroyed, and without remedy.