Matthew 24:50
The lord of that servant will come in a day when he is not looking for him, and in an hour of which he has no knowledge,
Matthew 24:42-44
Be watching, then! for you have no knowledge on what day your Lord will come.
1 Thessalonians 5:2-3
For you yourselves have the knowledge that the day of the Lord will come like a thief in the night.
Revelation 3:3
Keep in mind, then, the teaching which was given to you, and be ruled by it and have a change of heart. If then you do not keep watch, I will come like a thief, and you will have no knowledge of the hour when I will come on you.
Proverbs 29:1
A man hating sharp words and making his heart hard, will suddenly be broken and will not be made well again.