I Thessalonians 5:2, 4-6

For you yourselves know perfectly that the day of the Lord so comes as a thief in the night.

But you, brethren, are not in darkness, so that this Day should overtake you as a thief. You are all sons of light and sons of the day. We are not of the night nor of darkness. Therefore let us not sleep, as others do, but let us watch and be sober.