John 17:15
“I pray not that You should take them out of the world, but that You should keep them from the evil.”
Again He simplifies His language; again He renders it more clear; which is the act of one showing, by making entreaty for them with exactness, nothing else but this, that He has a very tender care for them. Yet He Himself had told them, that the Father would do all things whatsoever they should ask. How then does He here pray for them? As I said, for no other purpose than to show His love.
Source: Homilies on the Gospel of John (New Advent)