Augustine of Hippo

"And entered in to see." What Christ suffered, that suffereth also the Church; what the Head suffered, that suffer also the Members. "For the disciple is not above his Master, nor the servant above his Lord." ... If to Christ's Members thou belongest, come within, cling to the Head. Endure the tares if thou art wheat, endure the chaff if thou art grain. Endure the bad fish within the net if thou art a good fish. Wherefore before the time of winnowing dost thou fly away? …

Exposition on Psalm 41 ↗

Ambrose of Milan

Judas went out, and he spoke. He went out from the faith, he went out from the council and number of the apostles. He went out from Christ's banquet to the villainy of Satan; he went out from the grace that sanctifies to the noose that strangles. He went to speak vain things to infidels. He went outside, leaving behind the mysteries of life that lay within. He went out, for he had never known the mysteries that are contained in Scripture.

Commentary On Twelve Psalms 41:17 ↗

Thomas Aquinas

And sinners procure this by lying in ambush. Thus he first sets forth the manner of ambush. Second he shows the effect of the ambush, at "He came in." Concerning the first he does three things. For first he proposes the deceitful entry. Second, the feigned speech. Third, the insidious disposition. He says therefore, "If he came in to see me." Jerome has, "to visit"; as if to say: they did not come for the sake of friendship, but for the sake of spying. Thus the leaders of the Jews came to catch Jesus. …

Exposition on the Psalms of David ↗