In What Manner Christ Wills that All Shall Be One in Himself
12 So the Son of God Himself, the Word of God, Himself also the Mediator between God and men, the Son of man, equal to the Father through the unity of the Godhead, and partaker with us by the taking upon Him of humanity, interceding for us with the Father in that He was man, yet not concealing that He was God, one with the Father, among other things speaks thus: “Neither pray I for these alone,” He says, “but for them also which shall believe in me through their word; that they all may be one; as You, Father, art in me, and I in You, that they also may be one in us: that the world may believe that You have sent me. And the glory which You gave me I have given them; that they may be one, even as we are one.”
Source: On the Holy Trinity (New Advent)