John 17:24

Father I will that they also whom Thou hast given Me may be with Me where I am; that they may behold My glory, which Thou hast given Me: because Thou lovedst Me before the foundation of the world. He sets forth, says S. Chrysostom, "the rewards which await them after death, to show the love of Christ the more towards them, and to make them more resolute," and as S. Cyril says, "He wishes to teach that none will see His glory but those for whom He prayed, and who by Him are united to the Father. For He says, "those whom Thou hast given Me." And I earnestly desire that they may behold the glory, not only of my manhood exalted to the right Hand of the Father (as SS. Augustine and Cyril explain), but also of My Godhead. "For in this right does our blessedness essentially consist. But when He says, 'Because Thou lovedst Me,' it means, it is a manifest proof that Thou lovedst Me with an infinite love from all eternity, because in begetting Me, Thou gavest Me Thy glory and Godhead. But He begat Him not from mere love, but from His own natural fecundity as God. The Father therefore first begat the Son. He then loved Him whom He had begotten, for He had begotten One who was in all respects like Himself." So Jansenius.

Before the foundation of the world. This signifies that the world was not in any single part eternal, but, both in matter and form and all its other qualities, was created by God in the beginning of time, when its foundations were laid.