Matthew 24:50
the lord of that servant will arrive in a day when he doth not expect, and in an hour of which he doth not know,
Matthew 24:42-44
'Watch ye therefore, because ye have not known in what hour your Lord doth come;
1 Thessalonians 5:2-3
for yourselves have known thoroughly that the day of the Lord as a thief in the night doth so come,
Revelation 3:3
'Remember, then, how thou hast received, and heard, and be keeping, and reform: if, then, thou mayest not watch, I will come upon thee as a thief, and thou mayest not know what hour I will come upon thee.
Proverbs 29:1
A man often reproved, hardening the neck, Is suddenly broken, and there is no healing.