John 17:19

And for their sakes I sanctify Myself, that they also might be sanctified through the truth. 1st S. Augustine uses the word sanctify in its proper sense. I as the Son of God sanctify human nature which I have assumed, that by it I may sanctify the Apostles. As S. Augustine says, "When the Word was made flesh, He sanctified Himself in Himself; Himself the man, in Himself the Word, because the Word and the Man is one Christ. But He says it for the sake of His members; and for these I sanctify Myself, that is, them in Me, because in Me they are even Myself. That they also might be sanctified. What meaneth this, ' that they too,' but that they may be sanctified even as I, and in the Truth which I Myself am?"

2d, and correctly, "I offer Myself to Thee as a Holy Victim," i.e., within a few hours I shall offer It upon the Cross, so that they may by It "be sanctified in the truth," that is, that by Thy word which is truth, and no shadow, they may be sanctified, be truly Thine, and devote themselves, for Thee, to Apostolic labours; in order to convert all nations to Thee, and thus by the sufferings they endure, even martyrdom itself, they may offer themselves to Thee, just as I do Myself. So S. Chrysostom, S. Cyril (at great length), Rupertus, S. Thomas, Jansenius, Maldonatus, Toletus, Ribera, and others.