“When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me.”
John 13:21 — Greek Interlinear
Church Fathers on John 13:21
Our Lord after His twofold promise of assistance to the Apostles in their future labors, remembers that the traitor is cut off from both, and is troubled at the thought: When Jesus had thus said, He was troubled in spirit, and testified, and said, Verily, verily, I say to you, that one of you shall betray Me.
This did not come into His mind then for the first time; but He was now about to make the traitor known, and single him out from the rest, and therefore was troubled in spirit. The traitor too was now just about to go forth to execute his purpose. He was troubled at the thought of His Passion being so near at hand, at the dangers to which His faithful followers would be brought at the hand of the traitor, which were even now impending over Him. Our Lord deigned to be troubled…
His being troubled in spirit, was the human part, suffering under the excess of the spiritual. For if every Saint lives, acts, and suffers in the spirit, how much more is this true of Jesus, the Rewarder of Saints.