Augustine of Hippo

"The man of My peace, in whom I trusted, which did eat of My bread, hath enlarged his heel against Me" (ver. 9): hath raised up his foot against Me: would trample upon Me. Who is this man of His peace? Judas. And in him did Christ trust, that He said, "in whom I trusted"? Did He not know him from the beginning? Did He not before he was born know that he would be? Had He not said to all His disciples, "I have chosen you twelve, and one of you is a devil"? …

Exposition on Psalm 41 ↗

Ambrose of Milan

We need not imagine that Jesus did not know that Judas was going to betray him.… Of course Jesus knew it. But in order to emphasize how damnable was the deed, Jesus speaks of the hopes he had held regarding Judas' loyalty.… We come down more heavily on one in whom we say we had high hopes or great trust, if afterwards that person robs us of our hope and high opinion.… This is why Jesus says that he had hoped, it was as though he had a right to hope. …

Commentary On Twelve Psalms 41:21-22 ↗

Thomas Aquinas

"Even the man of my peace, in whom I trusted." Above, the Psalmist set forth the counsel of enemies plotting the death of Christ; here, however, he introduces the counsel of friends. And because Christ himself, in Jn. 13, introduces this word concerning Judas, therefore let us here explain this of Christ. Where he does two things. First the condition of Judas is described. Second, his guilt. …

Exposition on the Psalms of David ↗