Matthew 24:36
"But no one knows when that day or hour will come. Not even the angels in heaven or the Son [of God] know [when it will happen], but only the Father [does].
Acts 1:7
Jesus replied, "You are not permitted to know the [specific] time or date [when this will happen]. For the Father has appointed it [to happen] when He determines [the right time].
Matthew 25:13
Therefore, you should be watchful, for you do not know the day or hour [i.e., when the Son of man will return].
Mark 13:32
But no one knows when that day or that hour will come; not even the angels in heaven or the Son of God know, but only the Father does.
1 Thessalonians 5:2
for you know perfectly well that the day of the Lord [i.e., when He returns, See II Thess. 2:1-2] will arrive like a thief coming in the night.
Matthew 24:42
Therefore be alert, for you do not know on what day the Lord will come.
Matthew 24:44
Therefore, you also should be ready, for the Son of man will come at a time when you least expect Him.
2 Peter 3:10
But the day of the Lord will come as a thief [i.e., unexpectedly]. At that time the heavens will pass away with a loud noise and the elements [Note: This refers either to the heavenly bodies or to the material components of the universe], will be dissolved with intense heat. And the earth and its works [i.e., its activities] will be burned up. [Note: Some translations render this phrase as it is in some ancient manuscripts, "will be disclosed," or "will be laid bare"].
Revelation 3:3
So, remember how you have received and heard the message [i.e., they had eagerly accepted the Gospel]; [now] obey it and repent. For if you do not become [spiritually] alert, I will come as a thief [i.e. unexpectedly] and you will not know the [exact] time that I will come upon you [in judgment. See 2:16, 25].
Revelation 16:15
[Note: At this point the Lord's voice breaks into John's vision]. ("Look, I am coming like a thief. That person is happy who stays alert and is dressed [properly], so he does not appear naked and have to be shamefully exposed").