Cyril of Alexandria

I have been led on, He says, by very urgent reasons to give you, even before the time, this account of the events that will very shortly happen. For it will gratify those who hear Me, and bring them no slight advantage, if they know My aim in the matter. For to be recklessly wasteful in the use of words in meaningless dissertations is contrary to My custom and pleasure: but whatsoever seems likely to be fraught with no slight profit to you provided you have knowledge of it, this I feel constrained to instil in your ears. …

Commentary on the Gospel of John, Book 9 ↗

Augustine of Hippo

"From this time," Christ adds, "I tell you before it come; that when it is come to pass, ye may believe that I am He:" that is, I am He of whom the Scripture that preceded has just said, "He that eateth bread with me, shall lift up his heel upon me."

Tractates on John 59 ↗

Thomas Aquinas

Then when he says, I tell you this now, he gives the reason why he mentioned there was an exception. As if to say: I have been silent about his malice for a long time, but because the time is near when it will appear publicly, therefore, I tell you this now, before it takes place, that when it does take place you may believe that I am he who predicts the future and reveals the secrets of the heart: things which are characteristic of God. "The heart is deceitful above all things, and desperately corrupt; who can understand it? …

Commentary on John ↗

Bonaventure

From now on I tell you, before it happens, so that, when it has happened, you may believe that I am, namely God, who knows all things before they happen: Sirach 23: "To the Lord God, before they were created, all things are known," etc.

Commentary on John, Chapter 13 ↗