John 13:11

For He knew who was betraying Him, and that was why He said, "You are not all of you clean."

John 2:25

and did not need any one's testimony concerning a man, for He of Himself knew what was in the man.

Matthew 26:24-25

The Son of Man is indeed going as is written concerning Him; but alas for that man by whom the Son of Man is betrayed! It had been a happy thing for that man if he had never been born."

John 6:64-71

But there are some of you who do not believe." For Jesus knew from the beginning who those were that did not believe, and who it was that would betray Him.

John 13:2

While supper was proceeding, the Devil having by this time suggested to Judas Iscariot, the son of Simon, the thought of betraying Him, Jesus,

John 13:18

I am not speaking of all of you. I know whom I have chosen, but things are as they are in order that the Scripture may be fulfilled, which says, 'He who eats my bread has lifted up his heel against me.'

John 13:21

After speaking thus Jesus was troubled in spirit and said with deep earnestness, "In most solemn truth I tell you that one of you will betray me."

John 13:26

"It is the one," answered Jesus, "for whom I shall dip this piece of bread and to whom I shall give it." Accordingly He dipped the piece of bread, and took it and gave it to Judas, the son of the Iscariot Simon.

John 17:12

While I was with them, I kept them true to Thy name--the name Thou hast given me to bear--and I kept watch over them, and not one of them is lost but only he who is doomed to destruction--that the Scripture may be fulfilled.

Treasury of Scripture Knowledge

Summary

For he knew who should betray him; therefore said he, Ye are not all clean.

Bible References

General references

John 13:18
I am not speaking of all of you. I know whom I have chosen, but things are as they are in order that the Scripture may be fulfilled, which says, 'He who eats my bread has lifted up his heel against me.'
John 2:25
and did not need any one's testimony concerning a man, for He of Himself knew what was in the man.
John 6:64
But there are some of you who do not believe." For Jesus knew from the beginning who those were that did not believe, and who it was that would betray Him.
John 17:12
While I was with them, I kept them true to Thy name--the name Thou hast given me to bear--and I kept watch over them, and not one of them is lost but only he who is doomed to destruction--that the Scripture may be fulfilled.
Matthew 26:24
The Son of Man is indeed going as is written concerning Him; but alas for that man by whom the Son of Man is betrayed! It had been a happy thing for that man if he had never been born."